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High-Entropy Alloys: A Critical Review
Ming-Hung Tsai a & Jien-Wei Yeh b
a Department of Materials Science and Engineering, National Chung Hsing University,
T aichung 40227, T aiwan
b Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu
30013, T aiwan
Published online: 30 Apr 2014.
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Mater.Res.Lett.,2014
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High-Entropy Alloys:A Critical Review Ming-Hung Tsai a ?and Jien-Wei Yeh b ?
a
Department of Materials Science and Engineering,National Chung Hsing University,Taichung 40227,Taiwan;b
Department of Materials Science and Engineering,National Tsing Hua University,Hsinchu 30013,Taiwan
(Received 10February 2014;?nal form 2April 2014)
Supplementary Material Available Online
High-entropy alloys (HEAs)are alloys with ?ve or more principal elements.Due to the distinct design concept,these alloys often exhibit unusual properties.Thus,there has been signi?cant interest in these materials,leading to an emerging yet exciting new ?eld.This paper brie?y reviews some critical aspects of HEAs,including core e?ects,phases and crystal structures,mechanical properties,high-temperature properties,structural stabilities,and corrosion behaviors.Current challenges and important future directions are also pointed out.
Keywords :High-Entropy Alloys,High-Entropy Materials,Alloy Design,Mechanical Properties,Corrosion Resistance
1.Introduction Most conventional alloys are based on one principal element.Di?erent kinds of alloying ele-ments are added to the principal element to improve its properties,forming an alloy family based on the principal element.For example,steel is based on Fe,and aluminum alloys are based on Al.However,the number of elements in the periodic table is limited,thus the alloy families we can develop are also limited.If we think outside the conventional box and design alloys not from one or two ‘base’elements,but from multiple elements altogether,what will we get?This new concept,?rst proposed in 1995,[1]has been named a high-entropy alloy (HEA).[2]
HEAs are de?ned as alloys with ?ve or more princi-pal elements.Each principal element should have a con-centration between 5and 35at.%.[2,3]Besides principal elements,HEAs can contain minor elements,each below 5at.%.These alloys are named ‘HEAs’because their liquid or random solid solution states have signi?cantly higher mixing entropies than those in conventional alloys.Thus,the e?ect of entropy is much more pronounced in HEAs.Existing physical metallurgy knowledge and binary /ternary phase diagrams suggest that such multi-element alloys may develop several dozen kinds of phases and intermetallic compounds,resulting in complex and brittle microstructures that are di?cult to analyze and engineer,and probably have very limited practical value.
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Opposite to these expectations,however,experimental results show that the higher mixing entropy in these alloys facilitates the formation of solid solution phases with simple structures and thus reduces the number of phases.Such characters,made available by the higher entropy,are of paramount importance to the development and appli-cation of these alloys.Therefore,these alloys were named as ‘high-entropy’alloys.
Because of the unique multiprincipal element com-position,HEAs can possess special properties.These include high strength /hardness,outstanding wear resis-tance,exceptional high-temperature strength,good struc-tural stability,good corrosion and oxidation resistance.Some of these properties are not seen in conventional alloys,making HEAs attractive in many ?elds.The fact that it can be used at high temperatures broadens its spectrum of applications even further.Moreover,the fab-rication of HEAs does not require special processing techniques or equipment,which indicates that the mass production of HEAs can be easily implemented with existing equipment and technologies.More than 30ele-ments have been used to prepare more than 300reported HEAs,forming an exciting new ?eld of metallic mate-rials.This paper reviews some crucial aspects of the ?eld,including core e?ects,phase formation,mechani-cal properties,high-temperature properties,and corrosion
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behaviors.It also points out current challenges and future directions.The physical (magnetic,electrical,and ther-mal)properties of HEAs have been reviewed elsewhere [4]and are not discussed in this paper.
2.Core E?ects [3,5]The multiprincipal-element character of HEAs leads to some important e?ects that are much less pronounced in conventional alloys.These can be considered as four ‘core e?ects’.This section brie?y introduces and discusses the core e?ects.
2.1.High-Entropy E?ect.The high-entropy e?ect states that the higher mixing entropy (mainly con?gura-tional)in HEAs lowers the free energy of solid solution phases and facilitates their formation,particularly at higher temperatures.Due to this enhanced mutual solu-bility among constituent elements,the number of phases present in HEAs can be evidently reduced.According to G =H ?TS (where G is the Gibbs free energy,H is enthalpy,T is temperature,and S is entropy)entropy can stabilize a phase with higher entropy,provided that temperature is su?ciently high.For example,the melting phenomenon of a pure metal is due to the higher entropy of the liquid state relative to the solid state (according to Richard’s rule,[6]at melting point the entropy di?erence between the two states roughly equals the gas constant R ).Similarly,among the various types of phases in an alloy,those with higher entropy may also be stabilized at high temperature.In conventional alloys,solid solu-tion phases (including terminal and intermediate solid solutions)have higher mixing entropy than intermetal-lic compounds do.For HEAs,the di?erence in entropy between solid solutions and compounds is particularly large owing to the multiprincipal-element design.For example,the con?gurational entropy of an equimolar quinary random solid solution is 1.61R .This means that the entropy di?erence between an equimolar quinary solution and a completely ordered phase (whose entropy is negligible)is about 60%larger than the entropy dif-ference of the melting case mentioned above (i.e.60%larger than the entropy di?erence between liquid and solid states of pure metals).Thus,it is highly probable that solid solution phases become the stable phase in HEAs at high temperature.It is expected that with the increase of tem-perature,the overall degree of order in HEAs decreases.Thus,even those alloys that contain ordered phases in their cast state can transform to random solid solutions at high temperature.However,if the formation enthalpy of an intermetallic compound is high enough to overcome the e?ect of entropy,that intermetallic compound will still be stable at high temperature.
There is much evidence for the high-entropy e?ect.[7–13]Here we demonstrate this e?ect with Figure 1,which shows the XRD patterns of a series of binary to septenary alloys.It is seen that the
phases
Figure 1.The XRD patterns of a series alloy designed by the sequential addition of one extra element to the previous one.All the alloys have one or two major phases that have simple structures.
in quinary,senary,and septenary alloys remain rather simple:there are only two major phases,and these phases have simple structures such as BCC and FCC (note that the septenary alloy actually contain minor intermetallic phases,although not seen clearly in the XRD pattern).Such simple structures contradict conventional expectation:formation of various kinds of binary /ternary compounds.
Two myths regarding the high-entropy e?ect are discussed here.The ?rst myth is that the high-entropy e?ect guarantees the formation of a simple solid solution phase (order /disordered BCC /FCC)at high tempera-tures.This is not true.Actually,in the very ?rst paper of HEA,[2]the possibility of compound formation was already mentioned.In the same year,the existence of (Cr,Fe)-rich borides in the AlB x CoCrCuFeNi alloys was observed.[14]As mentioned previously,it is the compe-tition between entropy and enthalpy that determines the phase formation.The large negative formation enthalpy of the borides thus justi?es their stability at high tem-peratures.Similar phenomena have also been observed in other high-temperature annealing experiments.[15–17]The second myth is that only simple solid solution phases (BCC /FCC)are the desired phases for practical applica-tions of HEAs.This is also not true.It is true that these multiprincipal-element simple solid solution phases are unique to HEAs,and they can have outstanding proper-ties.However,as shown later,many HEAs containing intermediate phases also have great potential.Thus,the exploration of HEAs should not be limited to simple solid solution phases.
2.2.Sluggish Di?usion E?ect.It was proposed that the di?usion and phase transformation kinetics in HEAs are slower than those in their conventional counterparts.[18]This can be understood from two
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
Figure 2.Schematic diagram of the potential energy change during the migration of a Ni atom.The mean di?erence (MD)in potential energy after each migration for pure metals is zero,whereas that for HEA is the largest.[19]
aspects.Firstly,in HEA the neighboring atoms of each lattice site are somewhat di?erent.Thus,the neighbors before and after an atom jump into a vacancy are di?er-ent.The di?erence in local atomic con?guration leads to di?erent bonding and therefore di?erent local energies for each site.When an atom jumps into a low-energy site,it becomes ‘trapped’and the chance to jump out of that site will be lower.In contrast,if the site is a high-energy site,then the atom has a higher chance to hop back to its origi-nal site.Either of these scenarios slows down the di?usion process.Note that in conventional alloys with a low solute concentration,the local atomic con?guration before and after jumping into a vacancy is,most of the time,iden-tical.Tsai et https://www.doczj.com/doc/b24087782.html,ed a seven-bond model to calculate the e?ect of local energy ?uctuation on di?usion.[19]They showed that for Ni atoms di?using in Co–Cr–Fe–Mn–Ni alloys (which has a single-phase,FCC structure),the mean potential energy di?erence between lattice sites is 60.3meV,which is 50%higher than that in Fe–Cr–Ni alloys (see Figure 2).This energy di?erence leads
to a signi?cantly longer occupation time at low-energy sites (1.73times longer than that at high-energy sites).Indeed,di?usion couple experiments show that the acti-vation energy of di?usion in the Co–Cr–Fe–Mn–Ni alloys is higher than those in other FCC ternary alloys and pure elements (Table 1).[19]The di?usivity of Ni at the respective melting point of each metal is also calculated (Table 1).The slowest di?usion takes place again in the Co–Cr–Fe–Mn–Ni alloys.
Secondly,the di?usion rate of each element in a HEA is di?erent.Some elements are less active (for example,elements with high melting points)than others so these elements have lower success rates for jumping into vacancies when in competition with other elements.However,phase transformations typically require the coordinated di?usion of many kinds of elements.For example,the nucleation and growth of a new phase require the redistribution of all elements to reach the desired composition.Grain growth also requires the coop-eration of all elements so that grain boundaries can successfully migrate.In these scenarios,the slow-moving elements become the rate-limiting factor that impedes the transformation.
The slow kinetics in HEAs allows readily attainable supersaturated state and nano-sized precipitates,even in the cast state.[2,20,21]It also contributes to the excellent performance of HEA coatings as di?usion barriers.[22,23]Moreover,it allows better high-temperature strength and structural stability,which are discussed in Section 5.For the same reason,HEAs are also expected to have outstanding creep resistance.
2.3.Severe-Lattice-Distortion E?ect.The lattice in HEAs is composed of many kinds of elements,each with di?erent size.These size di?erences inevitably lead to distortion of the https://www.doczj.com/doc/b24087782.html,rger atoms push away their neighbors and small ones have extra space around.The strain energy associated with lattice distortion raises the overall free energy of the HEA lattice.It also a?ects the properties of HEAs.For example,lattice distortion impedes dislocation movement and leads to pronounced
Table 1.Di?usion parameters for Ni in di?erent FCC matrices.The compositions of Fe-Cr-Ni(-Si)alloys are in wt.%.[19]
D 0Q T m (T s )D T m Solute System (10?4m 2/s)
(kJ /mol)(K)Q /T m (10?13m 2/s)
Ni
CoCrFeMnNi 19.7317.516070.19750.95FCC Fe 331418120.1733 2.66Co 0.43282.217680.1596 1.98Ni
1.77285.317280.1651 4.21Fe-15Cr-20Ni 1.530017310.1733 1.33Fe-15Cr-45Ni 1.829316970.1727 1.73Fe-22Cr-45Ni 1.129116880.1724 1.09Fe-15Cr-20Ni-Si
4.8
310
1705
0.1818
1.53
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Figure 3.Hardness of the Al x CoCrCuFeNi alloys as a function of Al content.
solid solution strengthening (see Section 4.4).It also leads to increased scattering of propagating electrons and phonons,which translates to lower electrical and thermal conductivity.[4]
2.4.Cocktail E?ect.The properties of HEAs are cer-tainly related to the properties of its composing elements.For example,addition of light elements decreases the den-sity of the alloy.However,besides the properties of the individual composing elements,the interaction among the component elements should also be considered.For example,Al is a soft and low-melting-point element.Addition of Al,however,can actually harden HEAs.Figure 3plots the hardness of the Al x CoCrCuFeNi alloy as a function of Al content.It is clearly seen that the alloy hardens signi?cantly with the addition of Al.This is partly because of the formation of a hard BCC phase,and partly due to the stronger cohesive bonding between Al and other elements,and its larger atomic size.Thus,the macroscopic properties of HEA not only come from the averaged properties of the component elements,but also include the e?ects from the excess quantities produced by inter-elemental reactions and lattice distortion.
3.Phase and Crystal Structure In conventional alloys,phases are typically classi?ed into three types:ter-minal solutions,intermediate solutions,and intermetallic compounds.We can use similar,but expanded concepts to classify phases in HEAs.Terminal phases are phases based on one dominating element.The de?nition of intermetallic compounds is not changed:they are stoi-chiometric and have ?xed composition ratio.However,because phases in HEAs typically have a composition range rather than ?xed composition ratio,intermetallic compounds are rarely seen in HEAs.Solution phases are phases not belonging to the above two categories.This category includes the solid solutions based on both simple
(e.g.BCC and FCC)and complex structures (https://www.doczj.com/doc/b24087782.html,ves phase).
In the literature,phases in HEAs are usually clas-si?ed di?erently.They are often classi?ed as:random solid solution (e.g.FCC,BCC),ordered solid solution (e.g.B2and L12),and intermetallic phases (https://www.doczj.com/doc/b24087782.html,ves phases).This classi?cation may lead to some confusion because by de?nition,intermetallic phases can also be classi?ed as ordered solid solutions—they have compo-sition ranges and are typically ordered.In view of this,we suggest classifying the phases according to their structure (simple /complex)and ordering (ordered /disordered).A phase is said to be simple if its structure is identical to or derived from FCC,BCC or HCP https://www.doczj.com/doc/b24087782.html,ly,cI2-W,cF4-Cu,and hP2-Mg structures and their ordered versions (superlattices)such as cP2-CsCl (B2)and cP4-AuCu3(L12)structures are simple.[24]If a phase is not simple (https://www.doczj.com/doc/b24087782.html,ves phases),it is said to be complex .Therefore,the above three types now becomes:simple disordered phase (SDP),simple ordered phase (SOP),and complex ordered phase (COP).
3.1.Simple Solid Solution or Intermetallics?.One fundamental and important question regarding HEAs is:what kind of phase and crystal structure will form when we mix so many di?erent elements together?To the surprise of most people,simple structures (SDPs and SOPs)are the most frequently seen in as-cast HEAs (see Figure 1).These simple phases originate from the high-entropy e?ect mentioned previously.Besides sim-ple phases,di?erent kinds of COPs,such as σ,μ,Laves,etc.,are also observed in HEAs.Because simple-solution phases with more than ?ve elements are unique to HEAs,researchers have worked intensely to understand the conditions for their formation.
From the classic Hume-Rothery rules,factors that a?ect the formation of binary solid solutions include atomic size di?erence,electron concentration,and dif-ference in electronegativity.[25]Besides these factors,enthalpy and entropy of mixing are the most important phase formation parameters for HEAs.Zhang et al.[26]and Guo et al.[27]studied the e?ect of these parameters on the phase formation of HEAs and obtained similar conclusions:the formation of simple or complex phases depends mainly on the enthalpy of mixing ( H mix ),entropy of mixing ( S mix ),and atomic size di?erences (δ).In order to form sole simple phases (i.e.FCC,BCC,and their mixtures,including both ordered /disordered cases),the following conditions have to be met simulta-neously:?22≤ H mix ≤7kJ /mol,δ≤8.5,and 11≤ S mix ≤19.5J /(K mol).[27]This is shown in Figure 4,where the boundary of simple phases is shown.These conditions are quite logical: H mix cannot be too large in value because large positive H mix leads to phase separation and large negative H mix typically leads to D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
Figure 4.Superimposed e?ect of H mix,δ,and S mix on phase stability in equiatomic multicomponent alloys and BMGs.Notes:Blue symbols indicate the relationship between H mix andδ,while red ones represents that between S mix and δ.Symbol?represents equiatomic amorphous phase-forming alloys;?represents nonequiatomic amorphous phase-forming alloys; represents simple phases and represents inter-
metallic phases.The region delineated by the dash-dotted lines indicates the requirements for simple phases to form.[27]
intermetallic phases.δhas to be small enough since large δleads to excess strain energy and destabilizes simple structures. S mix has to be large enough because it is the main stabilizing factor for simple phases.If the tar-get of discussion is limited to SDPs only,the conditions are more strict:?15≤ H mix≤5kJ/mol,δ≤4.3,and 12≤ S mix≤17.5J/(K mol).[26]
The other criterion to judge whether or not sole simple phases will form in an HEA is the parameter ε=|T S mix/ H mix|.[28,29]Based on the concept of entropy–enthalpy competition(see Section2.1),εrep-resents the e?ect of entropy relative to that of enthalpy. Thus,largerεsuggests a higher possibility of forming SDP,which agrees well with the analysis.[28,29]A draw-back of the two criterions shown above is that even if an alloy is designed following these criterions,it can still contain intermetallic phases.This can be seen in Figure4. The‘solid solution’region delineated by the dash-dotted lines still contains triangles,indicating the existence of intermetallic phases.A new thermodynamic parameter has been proposed to solve this problem,and the results will be published soon.[30]
Some points of notice should be mentioned here: Firstly,the above analyses are based on the as-cast state.This is natural because most reported HEAs are in their as-cast state.Secondly,the phases observed macro-scopically in as-cast HEAs can contain atomic-scale decompositions/inhomogeneities.This is evidenced by detailed transmission electron microscopy(TEM)and atomic probe analysis.[21,31,32]Thirdly,in HEAs sim-ilar disordered and ordered versions of the same base structure often co-exist.[8,33–35]For example,coex-istence of BCC and ordered BCC(B2)phases was frequently reported.[8,21,34]Coexistence of FCC and ordered FCC(L12)phases was also observed.[35]When these phases have nearly identical lattice parameter, their XRD peaks overlap(except the superlattice peaks). Therefore,when the amount of the SOP is small,XRD may re?ect only the peaks belonging to SDP,even if SOP exists.[34,35]This indicates that TEM analysis is needed to really con?rm the existence of SOP.[34,35]
3.2.Crystal Structure of Simple Solid Solution Phases.If an HEA does crystallize into simple phases, what will the structure of the phase be?Virtually all sim-ple solid solution phase observed in HEAs have either BCC or FCC structures.[8,10,36,37]The most critical factor that decides whether an alloy crystallizes into BCC or FCC structure appears to be its VEC(valence electron concentration,the VEC of an alloy is calculated from
the Figure5.Relationship between VEC and the FCC,BCC phase stability for various HEA systems.Notes:Fully closed symbols
for sole FCC phases;fully open symbols for sole BCC phase;top-half closed symbols for mixed FCC and BCC phases.[38]
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1
4
weighted average VEC of the constituent components).Guo et al.summarized the relationship between VEC and structure of many HEAs (Figure 5).[38]They found that when the VEC of the alloy is larger than 8,the FCC structure is stabilized.When the VEC of the alloy is smaller than 6.87,the BCC structure is stabilized.Co-existence of FCC and BCC phase is observed at VEC values between 6.87and 8.[38]However,the mechanism behind the e?ect of VEC on phase formation has not been fully understood so far.
3.3.High-Entropy Bulk Metallic Glass.Although HEAs and bulk metallic glasses (BMGs)are both multi-component and their compositions look similar at ?rst glance,these two classes of materials are based on completely di?erent concepts.For HEAs,more than ?ve principal elements are required.In contrast,most BMGs are based on one or two principal elements.More importantly,BMGs are characterized by their amor-phous structure,but there is no structural requirement for HEAs.The concept of HEAs,however,triggered an idea:would there be good glass formers in HEAs?If so,how do we design high-entropy BMGs (HEB-MGs)with good glass-forming ability (GFA)and better properties?
Inoue’s empirical rules [39]state that (1)more than three composing element,(2)large atomic size di?er-ences,and (3)large negative mixing enthalpies favor the formation of BMGs.The ?rst rule is in line with the design concept of HEAs.Indeed,high con?gurational entropy in HEAs was found to be bene?cial for glass formation.This was evidenced by lower critical cooling rates in BMGs with higher S mix .[27]Another earlier study also reported similar ?ndings.[40]The second and third rules for BMG formation are exactly opposite to the requirements to form simple phases in HEAs (see Section 3.1).This suggests that one should choose HEAs that are predicted to form intermetallic phases rather than simple phases as candidates for HEBMGs.Indeed,very recently Guo et al.analyzed the H mix and δof some HEAs and BMGs and found that simple-solution-type HEAs and BMGs fall in opposite corners of the δ- H mix plot (shown in Figure 6[41]).They further pointed out that as long as the competition from intermetallic phases can be ruled out by composition adjustment,HEAs that locate in the amorphous phase region of the δ- H mix plot indeed solidify into metallic glasses.[41]This strat-egy has been successfully demonstrated in a series of Zr-containing alloys prepared via melt spinning.[41]
Not many HEBMGs have been fabricated till now.Most of these HEBMGs have diameters smaller than 3mm.[42–46]Takeuchi et al.successfully prepared Pd 20Pt 20Cu 20Ni 20P 20HEBMG with a maximum diam-eter of 10mm.[47]But they suggested that conventional GFA assessment parameters such as T rg (reduced
glass
Figure 6.The δ- H mix plot delineating the phase selection in HEAs.Note:The dash-dotted regions highlight the individual region to form simple solid solutions,intermetallic phases and amorphous phases.[41]
transition temperature normalized with liquidus temper-ature)cannot evaluate the GFA of HEBMG e?ectively.Other factors,e.g.Gibbs free energy assessments,need to be taken into account.[47]Apparently more study is needed to understand these issues.
The distinct composition design in HEAs brings with their amorphous structure other special prop-erties.For example,an extremely high crystalliza-tion temperature (probably the highest among reported BMG)of over 800?C and good performance as dif-fusion barrier between Cu and Si was observed in 20-nm-thick NbSiTaTiZr alloy ?lm.[23]Additionally,Zn 20Ca 20Sr 20Yb 20(Li 0.55Mg 0.45)20shows room temper-ature homogeneous ?ow and a plasticity of 25%,[44]which is in sharp contrast to the typical shear banding and brittle behavior of most BMGs.Very recently CaMgZn-SrYb,a high-entropy modi?cation of Ca 65Mg 15Zn 20BMG,has shown improved properties in orthope-dic applications.[48]CaMgZnSrYb not only has better mechanical properties,but also promotes osteogenesis and new bone formation after two weeks of implanta-tion.These examples indicate that high-entropy BMGs and amorphous ?lms do have great potential and deserve further exploration—which is good news for both com-munities.
3.4.Phases at Elevated Temperatures.As men-tioned in Section 3.1,our understanding of the phases in HEAs focuses mainly on their as-cast state.However,the cast state is typically not in thermodynamic equilibrium.For alloys that locate in the BCC or FCC phase region suggested by Guo et al.(see Figure 5[38]),phase trans-formation may be less signi?cant.For example,no phase formation was found in the Co–Cr–Fe–Mn–Ni FCC alloys during their high-temperature annealing.[14,17]For alloys that locate in the BCC +FCC phase region,
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
Figure 7.Relationship between the VEC and the presence of σphase after aging for a number of HEAs.Green and red icons indicate the absence and presence of σphase after aging,respectively.[52]
however,phase transformation will take place at higher temperatures.In the Al-Co-Cr-Cu-Fe-Ni system,anneal-ing at ～800?C or below increases the fraction of the BCC phase.[49]Annealing at temperatures higher than 800?C increases the fraction of the FCC phase.Because the FCC phase is ductile and the BCC phase is relatively brittle,annealing can be used to tune the mechanical properties.
Some alloys have phases that are stable at interme-diate temperatures only.These alloys may contain only simple phases in their as-cast state due to the higher cool-ing rate of Cu mold casting.Upon annealing,however,the intermediate-temperature phases will appear.For exam-ple,ηphase [17,50]and σphase [12,34,51]are known to form in some HEAs.One should pay great attention to the formation of these intermediate-temperature phases,because their formation can lead to signi?cant changes in mechanical properties.Tsai et al.studied the stabil-ity of the σphase.[52]They showed that the formation of the σphase is predictable:it is directly related to the VEC of the alloy.As shown in Figure 7,[52]there is a σ-phase-forming VEC range for HEAs based on Al,Co,Cr,Cu,Fe,Mn,Ni,Ti,and V.Alloys whose VEC fall in this range develop σphase upon annealing at 700?C.
https://www.doczj.com/doc/b24087782.html,puter-Aided Phase Prediction.The multi-principal-element nature of HEA translates to an immense amount of possible compositions.It takes huge amounts of time and cost to study all the composi-tions experimentally.Hence,it is critically important to implement highly e?cient,low-cost methods to assist experimental study.For example,phase diagram is one of the most important tools to understand an alloy sys-tem.However,developing the phase diagram of just one senary HEA requires tremendous e?orts—there are six composition axes!If the phase diagram could be reliably predicted with computational techniques,then experi-ments are only needed to verify some critical points on
the predicted phase diagram,and the work needed is signi?cantly reduced.
The main problem in applying existing phase-prediction techniques (e.g.CALculation of PHAse Dia-grams,CALPHAD)on HEAs is probably the lack of a suitable database for multicomponent systems.[53]Thus,Zhang et al.developed a thermodynamic database for the Al–Co–Cr–Fe–Ni alloy system by extrapolat-ing binary and ternary systems to wider composition ranges.[53]This database does not consider quaternary or quinary interaction https://www.doczj.com/doc/b24087782.html,ing their database,they obtained phase diagrams of the Al–Co–Cr–Fe–Ni system that agree with available experimental results.
In some cases,it seems that phase diagrams with reasonable accuracy can still be obtained even with-out the development of new databases.An Ni-based superalloy database was used to predict the equilib-rium phases and phase fractions of Al 0.5CoCrCuFeNi,Al 23Co 15Cr 23Cu 8Fe 15Ni 16and Al 8Co 17Cr 17Cu 8Fe 17Ni 33alloys.[12,31]Except for some minor discrepancies,[12]experiments and predictions agree with each other.These examples demonstrate the e?ectiveness of computational methods in predicting the phase of HEAs.Although the accuracy of computational phase predictions for other HEA systems (other than Al–Co–Cr–Cu–Fe–Ni)is still not clear (the only result appears to be not as pleas-ing [54]),it is greatly expected that these techniques will become important tools for the future design and development of HEAs.
3.6.Phase Evolutions in Representative Alloy Sys-tems.The phase evolutions in some important alloy systems are discussed,along with their mechanical prop-erties,in Sections
4.2and 4.3.This is because the mechanical properties of HEAs are directly related to the phases contained in the alloys (see Section 4.1).There-fore,the best way to understand the mechanical properties is to discuss phase evolution and mechanical properties together.4.
Mechanical Properties
4.1.Basic Concepts and Deformation Behaviors.Because of the wide composition range and the enor-mous number of alloy systems in HEAs,the mechanical properties of HEA can vary signi?cantly.In terms of hardness /strength,the most critical factors are:(1)Hardness /strength of each composing phase in
the alloy;
(2)Relative volume ratio of each composing phase;(3)Morphology /distribution of the composing
phases.
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Table 2.Phases in HEAs as categorized by hardness.Examples and typical hardness range for each category are also listed.
Typical Type
Examples
hardness (HV)Valence compounds
Carbides,borides,silicides
1000–4000Intermetallic phases with non-simple structures σ,Laves,η650–1300BCC and derivatives BCC,B2,Heusler 300–700FCC and derivatives
FCC,L12,L10
100–300
The ?rst factor is largely determined by the crystal struc-ture and bonding of each phase.In our experience,the phases can be roughly classi?ed into four categories each having a di?erent hardness range.This is provided in Table 2.It is important to note that the hardness ranges listed in Table 2are merely typical ranges and there could be exceptions.Valence compounds are based on very strong covalent bonding and are essentially ceramics.Thus,their hardness is the highest.Non-simple inter-metallic phases often lack easily accessible slip systems and dislocation activities are thus largely hindered.BCC and BCC-derivative structures (see the second paragraph of Section 3)are harder than their FCC counterparts because BCC-based structures have stronger directional bonding and lack a truly close-packed slip plane.[55,56]
The general rule to estimate the hardness /strength of an HEA is straight forward:the harder the phase (and the higher the fraction of the hard phase),the harder the alloy.When two HEAs have phases with similar hardness and relative fraction,the distribution of the phases can also play an important role.This is exempli?ed in later sections.The ductility of HEA is also related to the phase in the alloy.As can be expected,harder phases usually have lower ductility.
The deformation microstructure and mechanism in most HEAs is unclear.However,such information was revealed in a single-phase,FCC CoCrFeMnNi alloy via detailed TEM study.[57]It was found that at small strains (<2.4%),the deformation is governed by planar slip of 1/2 110 type dislocations on {111}planes.At a strain around 20%,the deformation behavior depends on the deformation temperature.At 77K,higher strain leads to the prevalence of deformation twinning.At 293K,how-ever,higher strain leads to the formation of dislocation cell structures.The texture evolution (during cold rolling)and recrystallization behavior in the same alloy have also been studied.[58]The texture after 90%cold rolling was predominantly brass-type,which indicates low stacking fault energy (SFE).Bhattacharjee et al.suggested that the lower SFE in HEAs is due to the higher free energy of the ‘perfect crystal’in HEAs.This is explained in further detail in the last paragraph of Section 5.The recrystalliza-tion texture in the CoCrFeMnNi alloy retains components from previous cold rolling,which is similar to low-SFE TWIP steels and 316stainless steel.However,the relative proportions of various texture components between HEA
and other low-SFE alloys are di?erent.The main rea-sons are the slower recrystallization rate in regions with brass texture,and the absence of preferential nucleation of brass-textured grains from shear bands.[58]The low SFE in the CoCrFeMnNi alloy as suggested by Bhattacharjee et al.[58]is indeed con?rmed by Zaddach et al.[59]They combined experiments with ?rst-principle calculations and concluded that the SFE of CoCrFeMnNi is between 18.3and 27.3mJ /m 2.This value is close to that of con-ventional low-SFE alloys such as AISI 304L and brass.
The cold deformation and annealing behaviors of another FCC-based HEA,the Al 0.5CoCrCuFeNi alloy,was also investigated.[60]Deformation twinning is observed again in this alloy.Prevalence of twinning appears to result from the blockage of local slip by the Widmanst?tten precipitates.The above results suggest that in FCC HEAs,dislocation slip and twinning are still the main deformation mechanisms.
4.2.The Al-Co-Cr-Cu-Fe-Ni Alloy System.Of all the HEA systems reported,Al-Co-Cr-Cu-Fe-Ni [7,8,21,35,36,49,60–68]and its Cu-free version Al-Co-Cr-Fe-Ni [69–74]have been studied most comprehensively.Most of the reported HEA systems emerge from them.The main di?erence between the two is the presence of Cu-rich interdendrite in the former.This is because Cu has positive mixing enthalpies with most of the other ele-ments,and is thus repelled to the interdendrite region.Additionally,remnant Cu in the dendrite region also clus-ters and forms various kinds of precipitates.[21,35,60]The main phases in cast Al-Co-Cr-Cu-Fe-Ni alloy include FCC,BCC /B2,and the Cu-rich phase (also has an FCC structure).The relative volume ratio of these phases depends on the composition.The relative volume of BCC and FCC phases is related to the VEC of the alloy.Higher VEC typically leads to more of the FCC phase,and vice versa.Al has the strongest e?ect in this regard,[36]and addition of Al leads to the transition of the FCC phase to the BCC phase.Additionally,when there is su?cient Al,BCC tend to further decompose to a (Al,Ni)-rich B2phase and a (Cr,Fe)-rich BCC phase that have almost identical lattice parameters.[8,21,71,74]The Cu-rich phase appears clearly when the concentration of Cu is higher than ～10at.%.Its fraction increases with the content of Cu.In general,hardness of the FCC phase is
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between HV 100–200.[7,8,70–72]Alloys having a sole FCC phase have ductilities between 20–60%,and usually exhibit signi?cant work hardening.[62,63,69]Hardness of the BCC /B2phase is typically between HV 500–600.Because addition of Al triggers the formation of hard BCC /B2phase,and hardness of the alloy increases with Al content [7,8,70–72](see Figure 3).Alloys hav-ing sole BCC /B2phases probably have ductilities less than 5%.[62]In terms of their plasticity,values of 30%or higher have been reported.[74]Superplasticity was observed in AlCoCrCuFeNi at 800–1000?C,and the elongation was between 405and 800%.[65]
E?ect of annealing on the mechanical properties of the Al-Co-Cr-Cu-Fe-Ni system depends on the phase transformation involved (see Section 3.4).When the selected annealing temperature favors the formation of BCC phase,the alloy becomes harder and more brit-tle.When the temperature selected increases the fraction of FCC phase,the alloys softens and becomes more ductile.It should be carefully noted that in this alloy sys-tem,a long annealing time may lead to the formation of σphase,[12]which hardens the alloy but remarkably reduces its ductility /plasticity.[12,34,51]
4.3.Derivatives of the Al-Co-Cr-Cu-Fe-Ni Alloy System.This section discusses the mechanical prop-erties of alloys derived from the Al-Co-Cr-Cu-Fe-Ni system.A system is said to be ‘derived’from Al-Co-Cr-Cu-Fe-Ni when the number of di?erent principal element between the two systems is less than two.For exam-ple,Al-Co-Cr-Cu-Ti is derived from Al-Co-Cr-Cu-Fe-Ni (replace Fe with Ti and remove Ni).
Addition of Ti to Al-Co-Cr-Cu-Fe-Ni usually leads to formation of intermetallic phases such as the Laves phase,[15,75–79]σphase,[17,75,76]Heusler phase,[17]η-Ni 3Ti,[17,50]and R phase.[76]This is because
Ti
Figure https://www.doczj.com/doc/b24087782.html,pressive true stress-strain curves of AlCoCrCuFeNiTi x alloys with x being 0,0.5,1,and 1.5.[77]
has large negative enthalpy of mixing with rest of the composition.These phases strengthen the alloy.For example,AlCoCrFeNiTi 0.5has a high yield strength of 2.26GPa and a plasticity of 23%(Figure 8).[77]The hard-ness of Al 0.5CoCrCuFeNiTi x alloy can be signi?cantly increased to HV 600or higher when x is larger than 1.[75]The hardness of Ti-containing alloys may further increase upon annealing owing to the formation of more intermetallic phases.[17,50]
Addition of Mo to the system generally leads to the formation of (Cr,Mo,Co,Fe)-rich σphase.[80–87]σphase is a very hard and brittle intermetallic phase.As mentioned previously,it signi?cantly enhances the hardness of the alloy but reduces its ductility /plasticity.For example,addition of 0.5mole fraction of Mo to AlCoCrFeNi raises its strength from 1,051to 2,757MPa.[86]
Addition of Mn leads to two representative sys-tems,the CoCrFeMnNi and Al x CrFe 1.5MnNi 0.5alloys.The CoCrFeMnNi alloy is a classic sole-FCC HEA and does not experience phase transformation when annealed.Therefore,it is a good model system to study the behav-ior of multiprincipal-element solid solutions and has been used to study the grain growth,[88]di?usion,[19]dislo-cation behavior,[57]and texture evolution [58]of FCC HEAs.This alloy is soft (yield strength ～170MPa),very ductile (elongation ～60%),and shows high strain hardening capability at room temperature.At 77K,its strength nearly doubles and its elongation increases to ～80%.[57]The Al 0.3CrFe 1.5MnNi 0.5alloy is a represen-tative age-hardening HEA.When aged between 600and 900?C,its hardness boosts from about 300HV to almost 900HV.[34,51,89]TEM observation shows that the hard-ening phenomenon is not from precipitation hardening,but from the transformation of the BCC matrix to the σphase during aging.[34]The hardening phenomenon in this alloy can actually be controlled to occur only near the surface,forming a surface hardening layer that signi?cantly improves wear resistance (see Section 4.5).
Addition of non-metallic elements such as Si and B leads to the formation of valence compounds such as silicides and borides.These compounds also lead to evident hardening.For example,the hardness of AlCoCr-FeNi Si [90]and Al B CoCrCuFeNi [14]are HV 738and HV 740,https://www.doczj.com/doc/b24087782.html,pound formation also causes loss of toughness.Addition of Si to AlCoCrFeNi by the equimolar ratio reduces its plastic strain from over 25%to ～1%.[90]It should be noted that although valence compounds are typically harder than inter-metallic phases,silicide /boride-containing alloys are not necessarily harder than alloys containing intermetallic phase.In the two alloys mentioned above (AlCoCrFeNi Si and Al B CoCrCuFeNi),the volume fractions of silicides and borides are not high,and the distribution of these compounds is quite localized.Hard phases with such morphology (isolated coarse laths)are less e?ective in D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
strengthening,particularly when they are embedded in an apparently softer matrix.Besides the above,many other elements have been added to the Al-Co-Cr-Cu-Fe-Ni sys-tem (e.g.Zr [91],Nd [91],Nb [92],V [93,94],Y [95],Sn [96,97],Zn [98],and C [99,100]).
4.4.Refractory HEA systems.Some researchers developed HEAs that are based on totally di?erent ele-ments.The most notable system is the refractory HEA system developed by Senkov et al.[10,37,54,101–106]These alloys are composed mainly of refractory ele-ments such as Cr,Hf,Mo,Nb,Ta,V,W,and Zr.The major phase in these alloys is typically BCC.Many of them even have a sole BCC structure.These BCC solid solutions have high strength ranging from 900to 1,350MPa.[37,101,105,106]Interestingly,such strength is several times higher than that of the weighted average strength of the composing elements.For example,the rule-of-mixture hardness of MoNbTaVW and HfNbTa-TiZr are 1,596and 1,165MPa,respectively.However,the hardness measured for these alloys are more than three times higher:5,250and 3,826MPa,respectively.Such high hardness is a result of the solid solution strengthen-ing e?ect which originated from the di?erence in atomic size and modulus among the composing elements.[37]Room temperature plasticity of refractory HEA is closely related to composition.The plastic fracture strain is less than 5%for many alloys.However,some alloys can be compressed to 50%without fracture.[37,103,106]It was suggested that the high plasticity in some alloys is owing to the prevalence of deformation twinning.[37,103]It is worth mentioning that refractory HEAs can show superb mechanical properties at elevated temperatures,which is described in Section
5.
4.5.Wear and Fatigue Properties.Wear properties of HEAs,under both abrasive [7,14,51,75,94,107]and adhesive [50,66,80]conditions,have been tested in a number of systems.The adhesive wear properties of tested HEAs are summarized in Figure 9.HEAs com-posed solely of SDPs typically do not show better wear properties than conventional alloys with similar hardness (https://www.doczj.com/doc/b24087782.html,pare Al 0.5CoCrCuFeNi and 316SS in Figure 9).Wear resistance is clearly enhanced in the presence of some B2or COPs (e.g.Al 2CoCrCuFeNi and AlCoCrFe 1.5Mo 0.5Ni).If COPs with high hardness become the main phase,wear resistance is often outstand-ing.Many HEA systems of this type have comparable or even better performances than conventional wear-resistant alloys such as SKD61tool steel (AISI H13)and SUJ2bearing steel (AISI 52100).[50,51,80,107]For example,the wear resistance of the AlCoCrFeMo 0.5Ni alloy is comparable to that of SUJ2(Figure 9).In particu-lar,the Al 0.2Co 1.5CrFeNi 1.5Ti alloy [50]has
signi?cantly
Figure 9.Relationship between hardness and adhesive wear resistances of various HEAs and conventional alloys.[50,66,80]
better wear resistance than SUJ2and SKH51(AISI M2,see Figure 9).Its hardness is similar to that of SUJ2,but its wear resistance is 3.6times that of the latter.The wear resistance of the Al 0.2Co 1.5CrFeNi 1.5Ti alloy is twice that of SKH51,but the hardness of the latter is a lot higher.The outstanding performance is owing to the higher hard-ness of HEA at high temperatures.Additionally,because the wear mechanism is mild oxidational wear,the better oxidation resistance in the Al 0.2Co 1.5CrFeNi 1.5Ti alloy is also bene?cial to its wear resistance.[50]
The Al 0.3CrFe 1.5MnNi 0.5alloy (see also Section 4.3)has a unique surface hardening phenomenon that can increase its wear resistance by ～50%,but only reduce its bending strain by 2%.This is achieved by limiting the formation of hard σphase at the surface region.Because the heterogeneous nucleation energy and strain energy near the free surface are lower than those in the interior of the alloy,one can carefully select the aging temperature so that the kinetics of the transfor-mation is su?cient high only at the near-surface region.The process is simple (atmospheric aging),applicable to objects with complex shapes,and o?ers a markedly better combination of mechanical properties than SUJ2(30%higher wear resistance and 300%larger maximum bending strain).
Preliminary fatigue results are also encouraging.Al 0.5CoCrCuFeNi alloy can show long fatigue lives at relatively high stresses,high endurance limits (540–945MPa)and endurance limit to ultimate tensile strength ratio (0.402–0.703).[67]These values are comparable to or even better than many conventional alloys,such as var-ious steels,Ti alloys,and Zr-based BMGs.[67]Although some degree of scattering in fatigue life was observed,it is probably due to defects introduced during sample prepa-ration.If defects can be carefully controlled,the fatigue resistance characteristics in Al 0.5CoCrCuFeNi are very promising.
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Figure 10.Hardness of various HEAs and conventional alloys as functions of temperature.Some of the data is collected from literature.[50,85]
5.High Temperatures Properties and Structural Stability Many HEAs have exceptional high-temperature strength /hardness,which originates from their excellent resistance to thermal softening.Figure 10shows the hot hardness of three HEAs and three con-ventional alloys as functions of temperature.[50,85]The AlCoCr 2FeMo 0.5Ni and Al 0.2Co 1.5CrFeNi 1.5Ti alloys have very high hardness at room temperature (more than two times higher than Inconel 718superalloy).Their hardness decreases slowly with the increase of temper-ature.SKH51and SUJ2also have very high hardness at room temperature (over HV 700).However,in con-trast to the gradual softening behavior for the two HEAs,SKH51and SUJ2start to soften drastically at 200and 600?C,respectively.This leads to a signi?cant di?er-ence in hardness for the four alloys at 800?C—the two HEAs are still more than two times harder than the Inconel 718superalloy,while the two conventional alloys become apparently softer than Inconel 718(Figure 10).At 1000?C,AlCoCr 2FeMo 0.5Ni is already more than three times harder than Inconel 718.Also note that even the soft,sole-FCC Al 0.5CoCrCuFeNi alloy is quite resistant to thermal softening.
Hsu et al.[85]calculated the high-temperature soft-ening coe?cient of the AlCoCr x FeMo 0.5Ni (x =0–2.0)
Table 3.Softening coe?cient of two AlCoCr x FeMo 0.5Ni alloys and two con-ventional high-temperature alloys above transition temperature (T T ).[85]Softening coe?cient
Alloy above T T
Cr-1.5?2.32E-4Cr-2?1.66E-4T-800?3.12E-4In 718
?3.55E-4
alloys from the hot hardness vs.temperature curves and found that above the transition temperature (onset tem-perature for rapid softening),the softening coe?cient of these HEAs are evidently lower than that of conventional high-temperature alloys such as Inconel 718and T800(Table 3).[85]Softening coe?cient of some alloys are even less than half that of Inconel 718.The resistance to thermal softening is mainly a result of the sluggish di?usion in HEAs.Above the transition temperature,deformation proceeds via di?usion-related mechanisms.Thus,the slower di?usion rate in HEAs can e?ectively reduce the degree of thermal softening.
Because the transition temperature and di?usion rate of metallic materials are directly related to the melting point of the material,it can be expected that refractory HEAs should have outstanding prop-erties in this regard.Indeed,W-containing refractory HEAs have excellent resistance to thermal softening.This is shown in Figure 11.[101]The yield
strengths
Figure 11.Yield strength as functions of temperature for the Nb 25Mo 25Ta 25W 25and V 20Nb 20Mo 20Ta 20W 20alloys and two superalloys.[101]
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of Nb 25Mo 25Ta 25W 25and V 20Nb 20Mo 20Ta 20W 20alloys remain virtually unchanged in the range of 600–1000?C.The two alloys have extremely high yield strength of over 400MPa at 1600?C.Owing to their good strength at high temperatures,some refractory alloys actually have higher speci?c yield strength than superalloys such as Inconel 718and Haynes 230at higher than 1000?C.[106]
Structural stability is an important issue for high-temperature applications.HEAs generally have good structural stability at high temperatures.This is owing to (1)slower kinetics due to the sluggish di?usion e?ect (Section 2.2);(2)reduced driving force to eliminate defects (e.g.grain boundaries,interfaces,etc.).The driv-ing force to eliminate defects originates from the free energy di?erence between defect-containing and defect-free crystals.However,the defect-free lattice in HEAs is still highly strained and full of atomic-scale zigzag,owing to the atomic size di?erences between the ele-ments.The strain energy of the distorted lattice raises the overall free energy,leading to a reduced energy di?erence between defect-containing crystal /amorphous structure and the defect-free crystal.[23,108]Thus,the driving force to eliminate defects is reduced.There is much evidence for the good structural stability of HEAs.For example,the activation energy of grain growth for the CoCrFeMnNi alloy (which has a sole FCC struc-ture)is 321.7kJ /mole ?1.[88]This value is twice that of AISI 304LN,indicating a signi?cantly slower kinetics for microstructural coarsening.[88]Growth of precipi-tates in HEAs is also slow.Precipitates in HEAs treated at moderate temperature (e.g.700–800?C)often still remain small—diameters on the scale of tens or hun-dreds of nanometers have been reported.[34,82]Another example is the NbSiTaTiZr amorphous alloy.The crys-tallization temperature of NbSiTaTiZr is higher than 800?C.[23]This temperature of stability is probably the highest among reported amorphous metals.The excellent structural stability comes not just from the above two rea-sons.NbSiTaTiZr was designed based on a free energy consideration.[23]Its composition was selected so that the non-crystalline random solid solution state has a low free energy.This lowers its driving force to crystallize into silicides.Additionally,the kinetics in this alloy is further slowed due to the high atomic packing density and high melting points of composing elements.6.Corrosion Properties The corrosion resistances of some HEAs have been tested in both NaCl and H 2SO 4solutions.[20,73,109–121]In both solutions,some HEAs show better corrosion properties than 304SS and even 304L SS and have good resistance to pitting.[109,115–117]Important factors include alloy composition and microstructure,particularly the amount and distribution of corrosion-resistant elements (such as Cr),and the presence of galvanic corrosion.Most of these tested
alloys are based on Co,Cr,Fe and Ni.Therefore,the cor-rosion behavior of the Co–Cr–Fe–Ni alloys is discussed ?rst,followed by the e?ect of elemental addition to the alloy system.
Corrosion in NaCl Solution :In NaCl solution,the CoCrFeNi single-phase FCC alloy has markedly better corrosion resistance than 304L SS.[111]This is probably owing to its high Cr and Ni content.Addition of Cu to the CoCrFeNi alloy leads to the formation of Cu-rich inter-dendrite phase,which su?ers from galvanic corrosion and severely degrades the corrosion resistance.[111,118]To make things worse,the passive ?lm on the Cu-rich interdendrite regions does not o?er good protection,which further narrows down the passivation region.[111]The corrosion property can be improved by reduc-ing the amount of Cu-rich phase via high-temperature annealing.[118]Addition of 0.5mole fraction of Al to the CoCrFeNi alloy leads to the formation of (Al,Ni)-rich BCC phase and causes galvanic corrosion in NaCl solution.[73]Al is also detrimental to the corrosion resis-tance of the Al x CrFe 1.5MnNi 0.5alloys.Addition of Al signi?cantly reduces the pitting potential and increases the area of localized /pitting corrosion of these alloys in NaCl solution.[114]Although it has higher pitting poten-tial,the passive region is less than that of 304SS.Addition of Mo to the Co 1.5CrFeNi 1.5Ti 0.5Mo x alloy is bene?cial because it evidently raises the pitting potential.[115,119]For example,Co 1.5CrFeNi 1.5Ti 0.5Mo 0.1alloy has a wide passivation region of 1.43V in 1M NaCl and does not su?er from any pitting.[116,119]
Corrosion in H 2SO 4Solution :In H 2SO 4solution,CoCrFeNi also has better corrosion resistance than 304SS.[117]Addition of Cu to the CoCrFeNi alloy deterio-rates its corrosion properties.Similar to the case in NaCl solution,this is due to the formation of the Cu-rich phase.The width of the passivation region is also evidently narrowed.[109,113]Addition of Al is also harmful.[114,117]It leads to the formation of a FCC+BCC or BCC+B2two-phase structure,in which the Ni,Al-rich BCC /B2phase is preferentially corroded.[74,117]Additionally,the existence of Al turns the passive ?lm porous and less protective.[117]Replacing Co with Mn in the Co–Cr–Fe–Ni alloy degrades its corrosion resistance in H 2SO 4solu-tion,and renders its resistance inferior to 304SS.[114]Addition of B to the Al 0.5CoCrCuFeNi alloy leads to the formation of Cr-rich borides and apparently lowers the Cr content in the matrix.[113]This renders the matrix much less corrosion resistant.Addition of Ti to the Co–Cr–Fe–Ni alloy does not a?ect its outstanding corrosion behavior.[119]Addition of Mo to the Co–Cr–Fe–Ni–Ti alloy is detrimental to the corrosion resistance in H 2SO 4solution.This is because of the formation of the (Cr,Mo)-rich σphase,which reduces the concentration of Cr in other phases.[119]The AlCu 0.5CoCrFeNiSi alloy has better general corrosion resistance than 304SS,but its passivation region is smaller.[109]
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7.Outstanding Issues and Future Directions HEA is an immense ?eld with a countless number of new alloy systems.Our understanding of these new materials is still very limited and preliminary.As mentioned in Section 4,our knowledge mainly focuses on the Al-Co-Cr-Cu-Fe-Ni system,its derivatives,and the refractory HEAs—just a very tiny fraction of the whole HEA world.More ele-ments and combinations need to be explored to further understand the potentials of HEAs.For example,light HEAs are of great interest.[122–124]Non-metallic ele-ments such as C,B,and N can also be incorporated to achieve even higher strength.[14,99,100,125,126]Addi-tionally,HEAs can also be prepared by other process and /or in other forms.For example,HEAs can be pro-cessed by a wrought process including homogenization,hot /cold working,and annealing [62,64]to eliminate casting defects and improve microstructure.HEA pow-ders can be prepared by ball milling.[98,127–131]The powders can subsequently be sintered to form bulk HEAs with ultra?ne structure.[98,127,129]Single-crystal of the Al 0.3CoCrFeNi HEA has also been prepared successfully by the Bridgman solidi?cation method.[132]Cemented carbides and cermets could be sintered by a proper HEA binder to reduce cost and improve resistance to softening.HEA coatings /claddings can also be prepared by sputter-ing or other cladding techniques.[22,23,73,133–140]
In terms of the phase and crystal structure of HEAs,most of our knowledge is based on the as-cast state (after vacuum arc melting).Very little is known about the equi-librium phases and phase diagrams,but these are key to the design and development of HEAs.Signi?cantly more combined experimental and computational works are needed in this regard.It is worth mentioning that although equimolar compositions are usually the easi-est access to a new alloy system,they probably do not possess the best combination of properties.Therefore,there is probably far more treasure in those non-equimolar alloys with carefully designed composition and tailored microstructures.A good approach is to start from equimo-lar alloys and then extract the desired non-equimolar composition from the equimolar alloy.
The mechanical properties of HEAs available are mostly about hardness and compressive properties.Because reasonable ductility is crucial to structural appli-cations,more studies on tensile behaviors are de?nitely needed.Additionally,except for a few examples,[57–59,141]not much is known about the deformation of HEAs,e.g.dislocation behavior,deformation twin-ning,deformation microstructures,texture evolution,stacking fault energy,etc.This information is the foundation for a thorough understanding of mechani-cal properties.Microstructural characterization in most works is only conducted by SEM.This is not su?-cient for unraveling the structure-property relationship in HEAs because all detailed microstructure observations reveal the existence of nano-sized or even atomic-scale
precipitations and /or decompositions.[21,31,32,34,35,98,142]More tests aimed at prolonged service and /or high-temperature applications are also required.These include but are not limited to:fatigue behavior,[67]oxida-tion resistance,[50,51,104]structural stability,and creep behavior.
HEAs can also be used in other applications.For example,HEAs can be used as hydrogen storage materials,[143,144]radiation resistant materials,[145]di?usion barriers for electronics,[22,23]precision resistors,[4,146]electromagnetic shielding materials,soft magnetic materials,[147]thermoelectric materials,functional coatings,and anti-bacterial materials.Because of the distinct design strategy and unique properties,HEAs and other high-entropy materials (e.g.high-entropy ceramics or even polymers)will probably ?nd applications in ?elds signi?cantly wider than those listed above.This exciting new virgin ?eld awaits exploration by more scientists.
Supplementary Online Material.A more detailed information on experiments is available at https://www.doczj.com/doc/b24087782.html,/10.1080/21663831.2014.912690Acknowledgements
MH Tsai gratefully thanks the ?nan-cial support from the National Science Council of Taiwan under grant NSC 102-2218-E-005-004.The authors acknowledge the valuable discussions with Yih-Farn Kao,Sheng-Chieh Liao,and Dr Kun-Yo Tsai.
References
[1]Huang KH,Yeh JW.A study on multicomponent alloy
systems containing equal-mole elements [M.S.thesis].Hsinchu:National Tsing Hua University;1996.
[2]Yeh JW,Chen SK,Lin SJ,Gan JY,Chin TS,Shun TT,
Tsau CH,Chang SY.Nanostructured high-entropy alloys with multiple principal elements:novel alloy design con-cepts and outcomes.Adv Eng Mater.2004;6:299–303.[3]Yeh JW.Recent progress in high-entropy alloys.Ann
Chim-Sci Mat.2006;31:633–648.
[4]Tsai MH.Physical properties of high entropy alloys.
Entropy.2013;15:5338–5345.
[5]Yeh JW.Alloy design strategies on high-entropy alloys.
JOM.2013.
[6]Gaskell DR.Introduction to the thermodynamics of
materials.3rd ed.Washinton (DC):Taylor &Francis;1995.
[7]Tong CJ,Chen MR,Chen SK,Yeh JW,Shun
TT,Lin SJ,Chang SY.Mechanical performance of the Al x CoCrCuFeNi high-entropy alloy system with multiprincipal elements.Metall Mater Trans A.2005;36:1263–1271.
[8]Tong CJ,Chen YL,Chen SK,Yeh JW,Shun TT,
Tsau CH,Lin SJ,Chang SY.Microstructure character-ization of Al x CoCrCuFeNi high-entropy alloy system with multiprincipal elements.Metall Mater Trans A.2005;36:881–893.
[9]Li A,Zhang X.Thermodynamic analysis of the sim-ple microstructure of AlCrFeNiCu high-entropy alloy
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
with multi-principal elements.Acta Metallurgica Sinica (English Letters).2009;22:219–224.
[10]Senkov ON,Wilks GB,Miracle DB,Chuang CP,Liaw PK.Refractory high-entropy alloys.Intermetallics.2010;18:1758–1765.
[11]del Grosso MF,Bozzolo G,Mosca HO.Determination of the transition to the high entropy regime for alloys of refractory elements.J Alloys Compd.2012;534:25–31.[12]
Ng C,Guo S,Luan J,Shi S,Liu CT.Entropy-driven phase stability and slow di?usion kinetics in an Al 0.5CoCrCuFeNi high entropy alloy.Intermetallics.2012;31:165–172.
[13]
Lucas MS,Wilks GB,Mauger L,Munoz JA,Senkov ON,Michel E,Horwath J,Semiatin SL,Stone MB,Abernathy DL,Karapetrova E.Absence of long-range chemical ordering in equimolar FeCoCrNi.Appl Phys Lett.2012;100:251907.
[14]
Hsu CY,Yeh JW,Chen SK,Shun TT.Wear resis-tance and high-temperature compression strength of Fcc CuCoNiCrAl 0.5Fe alloy with boron addition.Metall Mater Trans A.2004;35:1465–1469.
[15]
Zhang KB,Fu ZY.E?ects of annealing treat-ment on phase composition and microstructure of CoCrFeNiTiAl x high-entropy alloys.Intermetallics.2012;22:24–32.
[16]
Otto F,Yang Y,Bei H,George EP.Relative e?ects of enthalpy and entropy on the phase stability of equiatomic high-entropy alloys.Acta Mater.2013;61:2628–2638.
[17]Lin CW,Tsai MH,Tsai CW,Yeh JW,Chen SK.Microstructure and aging behavior of Al 5Cr 32Fe 35Ni 22Ti 6ternary-like high-entropy alloy.In preparation.
[18]
Cheng KH,Lai CH,Lin SJ,Yeh JW.Recent progress in multi-element alloy and nitride coatings sputtered from high-entropy alloy targets.Ann Chim-Sci Mat.2006;31:723–736.
[19]Tsai KY,Tsai MH,Yeh JW.Sluggish di?usion in Co–Cr–Fe–Mn–Ni high-entropy alloys.Acta Mater.2013;61:4887–4897.
[20]
Chen YY,Duval T,Hong UT,Yeh JW,Shih HC,Wang LH,Oung JC.Corrosion properties of a novel bulk Cu 0.5NiAlCoCrFeSi glassy alloy in 288?C high-purity water.Mater Lett.2007;61:2692–2696.
[21]
Singh S,Wanderka N,Murty BS,Glatzel U,Ban-hart J.Decomposition in multi-component AlCoCr-CuFeNi high-entropy alloy.Acta Mater.2011;59:182–190.
[22]
Tsai MH,Yeh JW,Gan JY.Di?usion barrier prop-erties of AlMoNbSiTaTiVZr high-entropy alloy layer between copper and silicon.Thin Solid Films.2008;516:5527–5530.
[23]
Tsai MH,Wang CW,Tsai CW,Shen WJ,Yeh JW,Gan JY,Wu WW.Thermal stability and performance of NbSiTa-TiZr high-entropy alloy barrier for copper metallization.J Electrochem Soc.2011;158:H1161–H1165.
[24]
Ferro P,Saccone A.Structure of intermetallic compounds and phases.In:Cahn RW,Haasen P,editors.Physi-cal metallurgy.4th ed.Amsterdam,the Netherlands:Elsevier Science B.V.;1996.
[25]Cahn RW,Haasen P,editors.Physical Metallurgy.4th ed.Amsterdam:Elsevier Science B.V.;1996.
[26]Zhang Y,Zhou YJ,Lin JP,Chen GL,Liaw PK.Solid-solution phase formation rules for multi-component alloys.Adv Eng Mater.2008;10:534–538.
[27]
Guo S,Liu CT.Phase stability in high entropy alloys:formation of solid-solution phase or amorphous phase.Prog Nat Sci:Mater Int.2011;21:433–446.
[28]Chen ST,Yeh JW.E?ect of mixing enthalpy,mixing
entropy and atomic size di?erence on the structure of multicomponent alloys [M.S.thesis].Hsinchu:National Tsing Hua University;2009.
[29]Yang X,Zhang Y.Prediction of high-entropy stabilized
solid-solution in multi-component alloys.Mater Chem Phys.2012;132:233–238.
[30]Tsai KY,Tsai MH,Yeh JW.To be submitted.
[31]Manzoni A,Daoud H,Mondal S,van Smaalen
S,V?lkl R,Glatzel U,Wanderka N.Investigation of phases in Al 23Co 15Cr 23Cu 8Fe 15Ni 16and Al 8Co 17Cr 17Cu 8Fe 17Ni 33high entropy alloys and comparison with equilibrium phases predicted by Thermo-Calc.J Alloys Compd.2013;552:430–436.
[32]Manzoni A,Daoud H,V?lkl R,Glatzel U,Wanderka
N.Phase separation in equiatomic AlCoCrFeNi high-entropy alloy.Ultramicroscopy.2013;132:212–215.[33]Wang YP,Li BS,Fu HZ.Solid solution or intermetallics
in a high-entropy alloy.Adv Eng Mater.2009;11:641–644.
[34]Tsai MH,Yuan H,Cheng G,Xu W,Jian WW,Chuang
MH,Juan CC,Yeh AC,Lin SJ,Zhu Y.Signi?cant hard-ening due to the formation of a sigma phase matrix in a high entropy alloy.Intermetallics.2013;33:81–86.
[35]Tsai MH,Yuan H,Cheng G,Xu W,Tsai KY,Tsai
CW,Jian WW,Juan CC,Shen WJ,Chuang MH,Yeh JW,Zhu YT.Morphology,structure and composition of precipitates in Al 0.3CoCrCu 0.5FeNi high-entropy alloy.Intermetallics.2013;32:329–336.
[36]Tung CC,Yeh JW,Shun TT,Chen SK,Huang YS,
Chen HC.On the elemental e?ect of AlCoCrCuFeNi high-entropy alloy system.Mater Lett.2007;61:1–5.[37]Senkov ON,Scott JM,Senkova SV,Miracle DB,Wood-ward CF.Microstructure and room temperature prop-erties of a high-entropy TaNbHfZrTi alloy.J Alloys Compd.2011;509:6043–6048.
[38]Guo S,Ng C,Lu J,Liu CT.E?ect of valence electron
concentration on stability of fcc or bcc phase in high entropy alloys.J Appl Phys.2011;109:103505.
[39]Inoue A.Stabilization of metallic supercooled liquid and
bulk amorphous alloys.Acta Mater.2000;48:279–306.[40]Xia MX,Zhang SG,Ma CL,Li JG.Evaluation of
glass-forming ability for metallic glasses based on order-disorder competition.Appl Phys Lett.2006;89:091917.[41]Guo S,Hu Q,Ng C,Liu CT.More than entropy in high-entropy alloys:forming solid solutions or amorphous phase.Intermetallics.2013;41:96–103.
[42]Chen YY,Hong UT,Yeh JW,Shih HC.Mechani-cal properties of a bulk Cu 0.5NiAlCoCrFeSi glassy alloy in 288?C high-purity water.Appl Phys Lett.2005;87:261918.
[43]Gao XQ,Zhao K,Ke HB,Ding DW,Wang WH,Bai HY.
High mixing entropy bulk metallic glasses.J Non-Cryst Solids.2011;357:3557–3560.
[44]Zhao K,Xia XX,Bai HY,Zhao DQ,Wang WH.Room
temperature homogeneous ?ow in a bulk metallic glass with low glass transition temperature.Appl Phys Lett.2011;98:141913.
[45]Cunli?e A,Plummer J,Figueroa I,Todd I.Glass
formation in a high entropy alloy system by design.Intermetallics.2012;23:204–207.
[46]Ding HY,Yao KF.High entropy Ti 20Zr 20Cu 20Ni 20Be 20
bulk metallic glass.J Non-Cryst Solids.2013;364:9–12.[47]Takeuchi A,Chen N,Wada T,Yokoyama Y,Kato H,
Inoue A,Yeh JW.Pd 20Pt 20Cu 20Ni 20P 20high-entropy alloy as a bulk metallic glass in the centimeter.Inter-metallics.2011;19:1546–1554.
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
[48]Li HF,Xie XH,Zhao K,Wang YB,Zheng YF,Wang
WH,Qin L.In vitro and in vivo studies on biodegradable CaMgZnSrYb high-entropy bulk metallic glass.Acta Biomaterialia.2013;9:8561–8573.
[49]Wen LH,Kou HC,Li JS,Chang H,Xue XY,Zhou
L.E?ect of aging temperature on microstructure and properties of AlCoCrCuFeNi high-entropy alloy.Inter-metallics.2009;17:266–269.
[50]Chuang MH,Tsai MH,Wang WR,Lin SJ,Yeh JW.
Microstructure and wear behavior of Al x Co 1.5CrFeNi 1.5Ti y high-entropy alloys.Acta Mater.2011;59:6308–6317.
[51]Chen ST,Tang WY,Kuo YF,Chen SY,Tsau CH,
Shun TT,Yeh JW.Microstructure and properties of age-hardenable Al x CrFe 1.5MnNi 0.5alloys.Mater Sci Eng A.2010;527:5818–5825.
[52]Tsai MH,Tsai KY,Tsai CW,Lee C,Juan CC,
Yeh JW.Criterion for sigma phase formation in Cr-and V-containing high-entropy alloys.Mater Res Lett.2013;1:207–212.
[53]Zhang C,Zhang F,Chen SL,Cao https://www.doczj.com/doc/b24087782.html,putational
thermodynamics aided high-entropy alloy design.JOM.2012;64:839–845.
[54]Senkov ON,Senkova SV,Woodward C,Miracle DB.
Low-density,refractory multi-principal element alloys of the Cr–Nb–Ti–V–Zr system:Microstructure and phase analysis.Acta Mater.2013;61:1545–1557.
[55]Shigenobu O,Yoshitaka U,Masanori K.First-principles
approaches to intrinsic strength and deformation of mate-rials:perfect crystals,nano-structures,surfaces and inter-faces.Modelling and Simulation in Materials Science and Engineering.2009;17:013001.
[56]Reed-Hill RE,Abbaschian R.Physical metallurgy prin-ciples.3rd ed.PWS-KENT;1991.
[57]Otto F,DlouhyA,Somsen C,Bei H,Eggeler G,George
EP.The in?uences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy.Acta Mater.2013;61:5743–5755.
[58]Bhattacharjee PP,Sathiaraj GD,Zaid M,Gatti JR,Lee
C,Tsai C-W,Yeh J-W.Microstructure and texture evo-lution during annealing of equiatomic CoCrFeMnNi high-entropy alloy.J Alloys Compd.2014;587:544–552.[59]Zaddach AJ,Niu C,Koch CC,Irving DL.Mechanical
properties and stacking fault energies of NiFeCrCoMn high-entropy alloy.JOM.2013;65:1780–1789.
[60]Tsai CW,Chen YL,Tsai MH,Yeh JW,Shun TT,
Chen SK.Deformation and annealing behaviors of high-entropy alloy Al 0.5CoCrCuFeNi.J Alloys Compd.2009;486:427–435.
[61]Zhang KB,Fu ZY,Zhang JY,Shi J,Wang WM,Wang
H,Wang YC,Zhang QJ.Annealing on the structure and properties evolution of the CoCrFeNiCuAl high-entropy alloy.J Alloys Compd.2010;502:295–299.
[62]Tsai CW,Tsai MH,Yeh JW,Yang CC.E?ect of tem-perature on mechanical properties of Al 0.5CoCrCuFeNi wrought alloy.J Alloys Compd.2010;490:160–165.[63]Wang FJ,Zhang Y,Chen GL,Davies HA.Tensile
and compressive mechanical behavior of a CoCrCu FeNiAl 0.5high entropy alloy.Int J Mod Phys B.2009;23:1254–1259.
[64]Kuznetsov AV,Shaysultanov DG,Stepanov ND,
Salishchev GA,Senkov ON.Tensile properties of an AlCrCuNiFeCo high-entropy alloy in as-cast and wrought conditions.Mater Sci Eng A.2012;533:107–118.
[65]Kuznetsov AV,Shaysultanov DG,Stepanov ND,
Salishchev GA,Senkov ON.Superplasticity of AlCoC
rCuFeNi high entropy alloy.Mater Sci Forum.2013;735:146–151.
[66]
Wu JM,Lin SJ,Yeh JW,Chen SK,Huang YS.Adhesive wear behavior of Al x CoCrCuFeNi high-entropy alloys as a function of aluminum content.Wear.2006;261:513–519.
[67]
Hemphill MA,Yuan T,Wang GY,Yeh JW,Tsai CW,Chuang A,Liaw PK.Fatigue behavior of Al 0.5CoCrCuFeNi high entropy alloys.Acta Mater.2012;60:5723–5734.
[68]
Liu ZY,Guo S,Liu XJ,Ye JC,Yang Y,Wang XL,Yang L,An K,Liu CT.Micromechanical characterization of casting-induced inhomogeneity in an Al 0.8CoCrCuFeNi high-entropy alloy.Scr Mater.2011;64:868–871.
[69]Shun TT,Du YC.Microstructure and tensile behav-iors of FCC Al 0.3CoCrFeNi high entropy alloy.J Alloys Compd.2009;479:157–160.
[70]
Wang WR,Wang WL,Wang SC,Tsai YC,Lai CH,Yeh JW.E?ects of Al addition on the microstructure and mechanical property of Al x CoCrFeNi high-entropy alloys.Intermetallics.2012;26:44–51.
[71]
Kao YF,Chen TJ,Chen SK,Yeh JW.Microstruc-ture and mechanical property of as-cast,-homogenized,and -deformed Al x CoCrFeNi (0≤x ≤2)high-entropy alloys.J Alloys Compd.2009;488:57–64.
[72]Li C,Li JC,Zhao M,Jiang Q.E?ect of aluminum con-tents on microstructure and properties of Al x CoCrFeNi alloys.J Alloys Compd.2010;504:S515–S518.
[73]Lin CM,Tsai HL.Evolution of microstructure,hardness,and corrosion properties of high-entropy Al 0.5CoCrFeNi alloy.Intermetallics.2011;19:288–294.
[74]
Wang YP,Li BS,Ren MX,Yang C,Fu HZ.Microstructure and compressive properties of AlCrFe-CoNi high entropy alloy.Mater Sci Eng A.2008;491:154–158.
[75]
Chen MR,Lin SJ,Yeh JW,Chen SK,Huang YS,Tu CP.Microstructure and properties of Al 0.5CoCrCuFeNiTi x (x =0–2.0)high-entropy alloys.Mater Trans.2006;47:1395–1401.
[76]
Shun TT,Chang LY,Shiu MH.Microstructures and mechanical properties of multiprincipal component CoCrFeNiTi x alloys.Mater Sci Eng A.2012;556:170–174.
[77]
Zhou YJ,Zhang Y,Wang YL,Chen GL.Solid solu-tion alloys of AlCoCrFeNiTi x with excellent room-temperature mechanical properties.Appl Phys Lett.2007;90:181904.
[78]Wang XF,Zhang Y,Qiao Y,Chen GL.Novel microstruc-ture and properties of multicomponent CoCrCuFeNiTi x alloys.Intermetallics.2007;15:357–362.
[79]
Zhang KB,Fu ZY,Zhang JY,Wang WM,Wang H,Wang YC,Zhang QJ,Shi J.Microstructure and mechanical properties of CoCrFeNiTiAl x high-entropy alloys.Mater Sci Eng A.2009;508:214–219.
[80]Hsu CY,Sheu TS,Yeh JW,Chen SK.E?ect of iron content on wear behavior of AlCoCrFe x Mo 0.5Ni high-entropy alloys.Wear.2010;268:653–659.
[81]
Hsu CY,Wang WR,Tang WY,Chen SK,Yeh JW.Microstructure and mechanical properties of new AlCo x CrFeMo 0.5Ni high-entropy alloys.Adv Eng Mater.2010;12:44–49.
[82]
Shun TT,Hung CH,Lee CF.The e?ects of secondary ele-mental Mo or Ti addition in Al 0.3CoCrFeNi high-entropy alloy on age hardening at 700?C.J Alloys Compd.2010;495:55–58.
[83]
Zhu JM,Zhang HF,Fu HM,Wang AM,Li H,Hu ZQ.Microstructures and compressive properties of
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
multicomponent AlCoCrCuFeNiMo x under-bar alloys.J Alloys Compd.2010;497:52–56.
[84]Zhu JM,Fu HM,Zhang HF,Wang AM,Li H,Hu ZQ.Microstructures and compressive properties of multi-component AlCoCrFeNiMo x alloys.Mater Sci Eng A.2010;527:6975–6979.
[85]
Hsu CY,Juan CC,Wang WR,Sheu TS,Yeh JW,Chen SK.On the superior hot hardness and softening resistance of AlCoCr x FeMo 0.5Ni high-entropy alloys.Mater Sci Eng A.2011;528:3581–3588.
[86]Shun TT,Chang LY,Shiu MH.Microstructure and mechanical properties of multiprincipal component CoCrFeNiMo x alloys.Mater Charact.2012;70:63–67.[87]
Juan CC,Hsu CY,Tsai CW,Wang WR,Sheu TS,Yeh JW,Chen SK.On microstructure and mechanical per-formance of AlCoCrFeMo 0.5Ni x high-entropy alloys.Intermetallics.2013;32:401–407.
[88]Liu WH,Wu Y,He JY,Nieh TG,Lu ZP.Grain growth and the Hall-Petch relationship in a high-entropy FeCr-NiCoMn alloy.Scr Mater.2013;68:526–529.
[89]
Tsao LC,Chen CS,Chu CP.Age hardening reaction of the Al 0.3CrFe 1.5MnNi 0.5high entropy alloy.Mater Des.2012;36:854–858.
[90]
Zhu JM,Fu HM,Zhang HF,Wang AM,Li H,Hu ZQ.Synthesis and properties of multiprincipal component AlCoCrFeNiSi x alloys.Mater Sci Eng A.2010;527:7210–7214.
[91]
Zhuang YX,Liu WJ,Chen ZY,Xue HD,He JC.E?ect of elemental interaction on microstructure and mechani-cal properties of FeCoNiCuAl alloys.Mater Sci Eng A.2012;556:395–399.
[92]Ma SG,Zhang Y.E?ect of Nb addition on the microstruc-ture and properties of AlCoCrFeNi high-entropy alloy.Mater Sci Eng A.2012;532:480–486.
[93]
Li BS,Wang YR,Ren MX,Yang C,Fu HZ.E?ects of Mn,Ti and V on the microstructure and properties of AlCrFeCoNiCu high entropy alloy.Mater Sci Eng A.2008;498:482–486.
[94]
Chen MR,Lin SJ,Yeh JW,Chen SK,Huang YS,Chuang MH.E?ect of vanadium addition on the microstruc-ture,hardness,and wear resistance of Al 0.5CoCrCuFeNi high-entropy alloy.Metall Mater Trans A.2006;37:1363–1369.
[95]Hu ZH,Zhan YZ,Zhang GH,She J,Li CH.E?ect of rare earth Y addition on the microstructure and mechanical properties of high entropy AlCoCrCuNiTi alloys.Mater Des.2010;31:1599–1602.
[96]Liu L,Zhu JB,Li L,Li JC,Jiang Q.Microstructure and tensile properties of FeMnNiCuCoSn x high entropy alloys.Mater Des.2013;44:223–227.
[97]Liu L,Zhu JB,Zhang C,Li JC,Jiang Q.Microstructure and the properties of FeCoCuNiSn x high entropy alloys.Mater Sci Eng A.2012;548:64–68.
[98]
Pradeep KG,Wanderka N,Choi P,Banhart J,Murty BS,Raabe D.Atomic-scale compositional charac-terization of a nanocrystalline AlCrCuFeNiZn high-entropy alloy using atom probe tomography.Acta Mater.2013;61:4696–4706.
[99]Shun TT,Du YC.Age hardening of the Al 0.3CoCrFe NiC 0.1high entropy alloy.J Alloys Compd.2009;478:269–272.
[100]
Zhu JM,Fu HM,Zhang HF,Wang AM,Li H,Hu ZQ.Microstructure and compressive properties of mul-tiprincipal component AlCoCrFeNiC x alloys.J Alloys Compd.2011;509:3476–3480.
[101]
Senkov ON,Wilks GB,Scott JM,Miracle DB.Mechani-cal properties of Nb 25Mo 25Ta 25W 25and V 20Nb 20Mo 20
Ta 20W 20refractory high entropy alloys.Intermetallics.2011;19:698–706.
[102]Senkov ON,Woodward CF.Microstructure and proper-ties of a refractory NbCrMo 0.5Ta 0.5TiZr alloy.Mater Sci Eng A.2011;529:311–320.
[103]
Senkov ON,Scott JM,Senkova SV,Meisenkothen F,Miracle DB,Woodward CF.Microstructure and elevated temperature properties of a refractory TaNbHfZrTi alloy.J Mater Sci.2012;47:4062–4074.
[104]
Senkov ON,Senkova SV,Dimiduk DM,Woodward C,Miracle DB.Oxidation behavior of a refrac-tory NbCrMo 0.5Ta 0.5TiZr alloy.J Mater Sci.2012;47:6522–6534.
[105]Yang X,Zhang Y,Liaw PK.Microstructure and com-pressive properties of NbTiVTaAl x high entropy alloys.Procedia Eng.2012;36:292–298.
[106]
Senkov ON,Senkova SV,Miracle DB,Woodward C.Mechanical properties of low-density,refractory multi-principal element alloys of the Cr–Nb–Ti–V–Zr system.Mater Sci Eng A.2013;565:51–62.
[107]
Chuang MH,Tsai MH,Tsai CW,Yang NH,Chang SY,Yeh JW,Chen SK,Lin SJ.Intrinsic surface harden-ing and precipitation kinetics of Al 0.3CrFe 1.5MnNi 0.5multi-component alloy.J Alloys Compd.2013;551:12–18.
[108]Huang PK,Yeh JW.Inhibition of grain coarsening up to 1000?C in (AlCrNbSiTiV)N superhard coatings.Scr Mater.2010;62:105–108.
[109]
Chen YY,Duval T,Hung UD,Yeh JW,Shih HC.Microstructure and electrochemical properties of high entropy alloys—a comparison with type-304stainless steel.Corros Sci.2005;47:2257–2279.
[110]
Chen YY,Hong UT,Shih HC,Yeh JW,Duval T.Electro-chemical kinetics of the high entropy alloys in aqueous environments—a comparison with type 304stainless steel.Corros Sci.2005;47:2679–2699.
[111]Hsu YJ,Chiang WC,Wu JK.Corrosion behavior of FeCoNiCrCu x high-entropy alloys in 3.5%sodium chlo-ride solution.Mater Chem Phys.2005;92:112–117.[112]
Chen YY,Hong UT,Yeh JW,Shih HC.Selected cor-rosion behaviors of a Cu 0.5NiAlCoCrFeSi bulk glassy alloy in 288?C high-purity water.Scr Mater.2006;54:1997–2001.
[113]
Lee CP,Chen YY,Hsu CY,Yeh JW,Shih HC.The e?ect of boron on the corrosion resistance of the high entropy alloys Al 0.5CoCrCuFeNiB x .J Electrochem Soc.2007;154:C424–C430.
[114]
Lee CP,Chang CC,Chen YY,Yeh JW,Shih HC.E?ect of the aluminium content of Al x CrFe 1.5MnNi 0.5high-entropy alloys on.the corrosion behaviour in aqueous environments.Corros Sci.2008;50:2053–2060.
[115]
Chou YL,Wang YC,Yeh JW,Shih HC.Pitting corro-sion of the high-entropy alloy Co 1.5CrFeNi 1.5Ti 0.5Mo 0.1in chloride-containing sulphate solutions.Corros Sci.2010;52:3481–3491.
[116]
Chou YL,Yeh JW,Shih HC.The e?ect of molybdenum on the corrosion behaviour of the high-entropy alloys Co 1.5CrFeNi 1.5Ti 0.5Mo x in aqueous environments.Cor-ros Sci.2010;52:2571–2581.
[117]
Kao YF,Lee TD,Chen SK,Chang YS.Electrochem-ical passive properties of Al x CoCrFeNi (x =0,0.25,0.50,1.00)alloys in sulfuric acids.Corros Sci.2010;52:1026–1034.
[118]
Lin CM,Tsai HL,Bor HY.E?ect of aging treat-ment on microstructure and properties of high-entropy Cu 0.5CoCrFeNi alloy.Intermetallics.2010;18:1244–1250.
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
[119]Chou YL,Yeh JW,Shih HC.E?ect of molybdenum on
the pitting resistance of Co 1.5CrFeNi 1.5Ti 0.5Mo x alloys in chloride solutions.Corrosion.2011;67:085002.
[120]Lin CM,Tsai HL.E?ect of annealing treatment
on microstructure and properties of high-entropy FeCoNiCrCu 0.5alloy.Mater Chem Phys.2011;128:50–56.
[121]Yu Y,Xie FQ,Zhang TB,Kou HC,Hu R,Li
JS.Microstructure control and corrosion properties of AlCoCrFeNiTi 0.5high-entropy alloy.Rare Metal Mater Eng.2012;41:862–866.
[122]Juan CC,Yeh JW,Chin TS,editors.A novel light
high-entropy alloy Al 20Be 20Fe 10Si 15Ti 35.E-MRS Fall Meeting 2009;Warsaw,Poland.
[123]Cotton J,Munitz A,Oliver R,Gomes R,Bourne G,
Kaufman M,editors.Search for lower density high entropy alloys.TMS2013;2013;San Antonio,TX.[124]Kecskes L,Atwater M,Hammond V,Maupin H,Darling
K,editors.In?uence of processing parameters on the microstructure and mechanical properties of lightweight high entropy alloys.TMS2013;2013;San Antonio,TX.[125]Tang WY,Yeh JW.E?ect of aluminum content on
plasma-nitrided Al x CoCrCuFeNi high-entropy alloys.Metall Mater Trans A.2009;40:1479–1486.
[126]Tang WY,Chuang MH,Lin SJ,Yeh JW.Microstruc-tures and mechanical performance of plasma-nitrided Al 0.3CrFe 1.5MnNi 0.5high-entropy alloys.Metall Mater Trans A.2012;43:2390–2400.
[127]Varalakshmi S,Kamaraj M,Murty BS.Synthesis and
characterization of nanocrystalline AlFeTiCrZnCu high entropy solid solution by mechanical alloying.J Alloys Compd.2008;460:253–257.
[128]Chen Y-L,Hu Y-H,Tsai C-W,Hsieh C-A,Kao S-W,
Yeh J-W,Chin T-S,Chen S-K.Alloying behavior of binary to octonary alloys based on Cu–Ni–Al–Co–Cr–Fe–Ti–Mo during mechanical alloying.J Alloys Compd.2009;477:696–705.
[129]Varalakshmi S,Rao GA,Kamaraj M,Murty BS.Hot
consolidation and mechanical properties of nanocrys-talline equiatomic AlFeTiCrZnCu high entropy alloy after mechanical alloying.J Mater Sci.2010;45:5158–5163.
[130]Varalakshmi S,Kamaraj M,Murty BS.Formation and
stability of equiatomic and nonequiatomic nanocrys-talline CuNiCoZnAlTi high-entropy alloys by mechani-cal alloying.Metall Mater Trans A.2010;41:2703–2709.[131]Chen Y-L,Tsai C-W,Juan C-C,Chuang M-H,Yeh J-W,
Chin T-S,Chen S-K.Amorphization of equimolar alloys with HCP elements during mechanical alloying.J Alloys Compd.2010;506:210–215.
[132]Ma SG,Zhang SF,Gao MC,Liaw PK,Zhang Y.A suc-cessful synthesis of the CoCrFeNiAl0.3single-crystal,high-entropy alloy by bridgman solidi?cation.JOM.2013;65:1751–1758.
[133]Chen JH,Hua PH,Chen PN,Chang CM,Chen MC,
Wu W.Characteristics of multi-element alloy cladding produced by TIG process.Mater Lett.2008;62:2490–2492.
[134]Dolique V,Thomann A-L,Brault P,Tessier Y,Gillon P.
Complex structure /composition relationship in thin ?lms of AlCoCrCuFeNi high entropy alloy.Mater Chem Phys.2009;117:142–147.
[135]Dolique V,Thomann AL,Brault P,Tessier Y,Gillon P.
Thermal stability of AlCoCrCuFeNi high entropy alloy thin ?lms studied by in-situ XRD analysis.Surf Coat Technol.2010;204:1989–1992.
[136]Lin YC,Cho YH.Elucidating the microstructure and
wear behavior for multicomponent alloy clad layers by in situ synthesis.Surf Coat Technol.2008;202:4666–4672.[137]Chen JH,Chen PN,Hua PH,Chen MC,Chang YY,Wu
W.Deposition of multicomponent alloys on low-carbon steel using gas tungsten arc welding (GTAW)cladding process.Mater Trans.2009;50:689–694.
[138]Chen JH,Chen PN,Lin CM,Chang CM,Chang YY,
Wu W.Characterization of multi-element alloy claddings manufactured by the tungsten inert gas process.Surf Coat Technol.2009;203:2983–2988.
[139]Lin YC,Cho YH.Elucidating the microstructural and
tribological characteristics of NiCrAlCoCu and NiCrAl-CoMo multicomponent alloy clad layers synthesized in situ.Surf Coat Technol.2009;203:1694–1701.
[140]Zhang H,Pan Y,He YZ.E?ects of annealing on the
microstructure and properties of 6FeNiCoCrAlTiSi high-entropy alloy coating prepared by laser cladding.J Therm Spray Technol.2011;20:1049–1055.
[141]Zhu C,Lu ZP,Nieh TG.Incipient plasticity and disloca-tion nucleation of FeCoCrNiMn high-entropy alloy.Acta Mater.2013;61:2993–3001.
[142]Singh S,Wanderka N,Kiefer K,Siemensmeyer K,
Banhart J.E?ect of decomposition of the Cr–Fe–Co rich phase of AlCoCrCuFeNi high entropy alloy on magnetic properties.Ultramicroscopy.2011;111:619–622.
[143]Kao YF,Chen SK,Sheu JH,Lin JT,Lin WE,Yeh JW,
Lin SJ,Liou TH,Wang CW.Hydrogen storage properties of multi-principal-component CoFeMnTi x V y Zrz alloys.Intl J Hydrog Energy.2010;35:9046–9059.
[144]Kunce I,Polanski M,Bystrzycki J.Structure and hydro-gen storage properties of a high entropy ZrTiVCrFeNi alloy synthesized using Laser Engineered Net Shaping (LENS).Int J Hydrog Energy.2013;38:12180–12189.[145]Nagase T,Anada S,Rack PD,Noh JH,Yasuda H,Mori H,
Egami T.Electron-irradiation-induced structural change in Zr–Hf–Nb alloy.Intermetallics.2012;26:122–130.[146]Chen SK,Kao YF.Near-constant resistivity in 4.2-360
K in a B2Al 2.08CoCrFeNi.AIP Adv.2012;2:012111.[147]Zhang Y,Zuo T,Cheng Y,Liaw PK.High-entropy alloys
with high saturation magnetization,electrical resistivity,and malleability.Sci Rep.2013;3:1455.
D o w n l o a d e d b y [112.83.53.115] a t 17:21 08 M a y 2014
政府申请报告要怎么写呢?以下是为大家分享的3篇政府申请报告范文，供大家参考借鉴，欢迎浏览! 政府申请报告范文一： 关于向xx人民政府申请xx项目优惠政策的报告 xx人民政府： xx旅游地产暨现代农业建设项目是由(陕西xx集团)下属陕西xx房地产开发有限公司与xx房地产开发有限公司共同投资，根据《汉中市保护利用总体规划》，本着保护性利用自然资源的原则，在兼顾环境效益，合理利用生态资源，统筹城乡发展的基础上，力图打造的一个具有养生体验功能的高科技集旅游地产和现代农业示范区有机整合的地方发展项目。 一、xx旅游地产暨现代农业建设项目简介 xx旅游地产暨现代农业建设项目，将充分运用“文化传承、产品核心竞争力、价值附着”三大策略、“传统农业、现代农业、未来农业”三大板块、“互惠、分享、共赢”三大原则，进行整体规划。项目规划将综合考虑国家及汉中生态保护相关政策，把协调发展“三农问题”作为根本出发点。项目结合项目地良好的自然环境、当前现代农业的发展契机、西北地区休闲市场巨大需求，结合项目单位自身的人才、技术、管理、资金等资源等优势条件，利用农业为主线的链条式发展，以高端科技农业为主打，以规模特色农业为品牌，以休闲体验旅游为提升，将农业和旅游产业有机结合。建设国内外先进农业技术的引进转化示范区、农业专家课题示范区和自驾旅游集散中心。带动旅游观光、生态体验、餐饮住宿等辐射经济效益的升级。体现休闲自然的生活态度和生活方式，成为全国性的农业科技示范教育基地。实现第一产业、第二产业和第三产业的联动、互利和产业链升级发展。 xx项目以农业发展为基础，休闲养生体验为主题，旅游产业为拓展。项目实施后，将积极促进和改善xx区域的生态环境,打造优质生态宜居游乐生活，增进居民幸福度和营造社会和谐度。 项目总投入约亿，项目直接收益较高，可带来超过2亿的税收和6亿的衍生收益，并能解决农村剩余劳动力2000以上，可为这些劳动力带来每年2万元以上的收入，给武乡区域带来极大的综合效益。 二、项目投资单位简介 本项目投资单位：陕西xx房地产开发有限公司;具体实施单位：xx房地产开发有限公司;两公司均为陕西xx集团全资下属单位。 陕西xx集团是经由区政府领导、经贸局和xx房地产开发有限公司共同努力引入汉中，并成功注资落户的外来企业。 陕西xx集团，是以煤炭、电力为主导产业，以资源综合开发利用为宗旨，坚持节能环保发展观的新型能源企业。该公司先后被榆林市委、市人民政府授予“榆林市十佳企业”、“榆林市非公有制纳税十强企业”、“挂牌重点保护
小学三年级日记范文五篇 导读：本文小学三年级日记范文五篇，仅供参考，如果觉得很不错，欢迎点评和分享。 【篇一】 今天我学会了包包子，以前我是不会包包子的，可是现在就不一样了，下面我就让你看看我是如何学会包包子的。 我是向我奶奶学的包包子的。奶奶说首先要把面粉掺水和匀，然后揉搓直至像发酵的长面包。把包子馅事先切好放一边，等我把像长面包的面粉切一节一节的，然后把一节搓好的面粉放在手里用擀面杖推平，在吧馅放进去，然后再把面皮四圈包严就好了。 这就是我学会包包子的经验。【篇二】 今天奶奶带着我和哥哥一起去买菜。我们买了：豆腐、肉、小面条和疙瘩面。买好菜我们就回家了，在回家的路上，我和哥哥在前面走，奶奶在后面走，忽然奶奶跌倒在地上，手上的菜都掉到了地上，二块五角的豆腐都摔碎了，我们连忙去扶奶奶，我问奶奶：“奶奶，你怎么样呀？疼不疼？”奶奶站起来说：“没事的。”我在想：可能是奶奶为我们的安全就一直盯着我们，但是一只脚没走好就跌倒在地上了。我看到奶奶把手跌流血了，裤子跌破了，腿跌疼了，可是嘴上却说没事。我觉得大人现在做的事情都是为我们好，所以等我们长大了一定要好好孝敬他们。【篇三】 今天中午，爸爸妈妈带我一起去看家具。那儿的家具五花八门。
有形态各异的沙发，这些沙发有的像ok形的手指，有的是一个香蕉形，长的、圆的、方的，各式各样、千姿百态，看得我眼花缭乱。 我们来到二楼，那里摆着各式各样的床和橱。这些床有的是红色，有的是白色，还有的是黄色，真是五颜六色。我特别喜欢那张洁白的橱，在电灯的照耀下，看上去好亮。 到达三楼，那里有好多房间，每间房子都摆着一套家具，我左看看右看看，这套也好，那套也不错，不知道选择哪一套。最终，我们选了最漂亮的一套，看上去既简洁又大方，就买了下来。我特别高兴！【篇四】 今天我和妹妹去吃必胜客。 终于上菜了。妹妹想去拿牛排却被烫到手了。接着妈妈想去切牛排，也被烫到手了。不过牛排还是很好吃。上披萨了。我想去拿披萨却没看到牛肉，手放到了牛排上。啊，我的手也快被烫成“人排了”。我烫的这下好像是最疼得。我用凉水洗了好多遍，也只缓解1分钟左右。上冰激凌了！妹妹动作太快了，一下子就把两个冰激凌全抢了过来。太可气了！我真想发一下脾气。 总之，今天玩的很开心。【篇五】 今天早上，我在换衣服的时候就发现取暖气忽然不亮了。 晚上，妈妈说我买的手表带子已经在常州大润发里了，取暖器又刚好坏掉了，我就乘机去大润发玩！嘿嘿，我的想法不错吧，没等我说，妈妈就知道取暖器已经坏掉了，她说：“这可怎么办呀！今天还要洗澡呢！”只见那取暖器的管子上全都是蒸气，管子发黑，上面还
( 离职报告) 姓名：____________________ 单位：____________________ 日期：____________________ 编号：YB-BH-050156 员工辞职报告范文简单版Model text of employee resignation report
员工辞职报告范文简单版 尊敬的x总： 您好! 在经过内心多次痛苦挣扎和深思熟虑之后，我终于鼓起勇气写下了这封辞职信。对于这种勇气，我将其称为“成长的勇气”。 我来公司已经有一年多的时间了，这一年来佳联公司在飞速发展，我也在快速成长，我也深知在我成长的背后是领导的信任与潜心栽培，同事们的支持与帮助。 20xx年，对我来说是至关重要的一年，我很庆幸能够在这样的公司，这样的部门，这样的工作环境中迅速成长，适应社会。我的家人经常用这样一句话来教导我“找一个好企业容易，遇到一个好领导不容易”，我很幸运的在漫漫职业生养的伊始便遇到了您这样一位亦师亦友的好领导，我也很感激这一年来您对我犹如兄长般的关怀，支持与信任。在公司的这些日子，对于每一项工作任务，我都用心尽力，按时保量，加班加点的完成。我告诉自己，只有这样才能对得起领导在我身上所花费的心血。 坦白讲，最近几个月所遇到的许多事，让我重新举棋不定。但诚信或者忠诚，并不机械的等于终身服务于一家公司。人和企业都在时刻改变着，对于企业而言，
随着公司的发展变迁，过去适合的员工未来可能不再适合他的职位，对于个人来说，一个公司过去可能是他最佳的选择，随着时间的流逝，现在可能已经无法激发他最大限度的发挥他的激情和才干。我觉得现在是我该下定决心的时候了。 虽然做出这样的决定也会感觉到很痛苦，现在的我也只能很遗憾的说辜负了领导对我的深切期望，只能深深的说道一声对不起! 我考虑在辞呈递交之后的一月内离开，这样您将有时间去寻找适合人选，来填补因我离职而造成的空缺，同时我也能够协助您对新人进行培训，使他尽快熟悉工作。另外，如果您觉得我在某个时间内离职比较适合，不防给我个建议。 真诚的感谢您这一年来对我的厚爱，对我自身存在的缺点的包容，以及对我在工作中所存不足的指正。您那颗正直的心，满怀激情的人生态度，宽广的胸怀，机敏的处事方式，必将令我受用终身。我也很真诚的感谢和我一起工作的同事们，我曾经和他们度过了一段非常快乐的，令人难忘的时光。这样的深情，我铭记在心，这样的财富，将伴我一生。 无论走到哪里，我都会为我曾经是本公司的一员感到自豪，在这工作的日子是我宝贵的财富!最后祝公司的事业蒸蒸日上，业务高速上升。 此致 敬礼! 辞职人：xxx 20xx年x月x日 尊敬的公司领导： 首先致以我深深地歉意，怀着及其复杂而愧疚的心情我写下这份辞职信，很
本文部分内容来自网络整理所得，本司不为其真实性负责，如有异议或侵权请及时联系，本司将立即予以删除！ == 本文为word格式，下载后可方便编辑修改文字！ == 向政府写申请书范文 向政府写申请书范文：企业向政府申请书范文 ******建设局： 为了更好的贯彻落实国家对资源综合利用的指导思想，促进合理的节约资源，提高资源利用率，保护环境实现经济社会的可持续发展的战略方针。 ************有限责任公司顺应形势发展，准备在******投资建设一条具有轻质、阻燃、保温、抗震性强并具有可持续发展的轻集料小型空心砌块建筑材 料生产线。 此项目的投资建设能达到节约能源、保护土地、变废为宝及综合治理环境 污染的目的。 投资建设此项目我公司具有以下优势： 一、轻集料小型空心砌块是以矿渣、炉渣、粉煤灰加有石硝为骨料，以水泥为胶结料，被广泛使用于工业与民用建筑的非承重砌块、承重砌块、保温块。 是一种节能、节土、利废的可持续发展的建筑材料。 该产品生产工艺无二次污染产生，市场前景广阔变废为宝，造福后代并具 有极高的社会效益和环境效益。 而我公司经营煤矿及煤炭销售多年，常年与矿渣、粉煤灰、水泥等物接触。 二、我公司为******热力公司供运供热用煤已有多年，合作非常融洽。
随着******城市建设规模的不断扩大，******热力公司现在每年冬季供热用煤需要4万多吨，为了保证冬季的正常供暖，秋季储存煤就非常关键，但是热力公司的场地有限，无法大量储存煤，加之供热产生的炉渣占地面积也很大。 为此双方约定由我公司申请30亩土地，其中一半无偿作为热力公司储煤场地，一半用于我公司建设轻集料小型空心砌块生产线使用，同时供热产生的炉渣及时运送到本厂作为生产原料。 充分体现了双方互利互惠的原则。 综上所述，建设轻集料小型空心砌块生产线，即符合国家产业政策，同时为确保******冬季正常供暖，热力公司秋季储煤的问题也得到了解决。 因此，恳请******建设局审批30亩土地作为************有限责任公司建设轻集料小型空心砌块生产线和******热力公司储煤场地为盼。 ************有限责任公司 20**年月日 向政府写申请书范文：向政府申请资金请示范文 县政府： XX镇政府办公楼建于X年X月，迄今XX年，由于该楼建筑时间长，加之建筑质量不好等原因，部分房间的墙体出现裂缝，虽小有修缮但仍存在屋顶掉块、墙围脱落等现象，该楼已存在安全隐患，不适宜继续办公，必须进行修缮。 经多方论证，修缮费用预算为XX万元，因镇政府资金短缺，特向县政府申请修缮办公楼经费，我们一定加强对招投标和工程质量的管理，指派专人负责办公楼修缮事宜，做到专款专用，严格质量、严格纪律，请予以支持为盼。 当否，请批示。 附：XX镇政府办公楼修缮预算开支一览表。 X县X镇人民政府
小学三年级日记精选范文 小学三年级日记范文 写作有助于大脑开发，思维开阔，以下是本人为大家编辑的小学生日记范文，欢迎大家阅读！ 夜 夜，静静的，月光照在大地上。这倒使我想起李白的“床前明月光，疑是地上霜”诗句。月光是那么纯，那么真。 天上的星星，像一个个调皮的孩子。一闪一闪的小眼睛望着大地，像在寻找什么。月亮妈妈跳起了优美的舞蹈。它放射的光芒，是那么的柔和。 万物在月光的照射下，一切都变成了银白色。我走进了一个童话的世界，一个美丽的世界。它是那么神奇。河面上，倒映着那明亮的月亮。我捡起一块石头。地面上，灯火辉煌。家家户户点着灯火，真像天上的星星。马路上，一辆辆“俊马”在飞奔。 啊!美丽的夜呀，我为你的美而感到骄傲。 水仙花 我最喜欢水仙花，喜欢它的外表，更喜欢它的“内心”。它虽然没有牡丹花那样娇贵，没有太阳花那样红艳，没有菊花那样引人注意，也没有腊梅花那样清香醉人。可是水仙花亭亭玉立，玉洁冰清。还有着顽强的生命力。” 水仙花素有“凌波仙子”的美称。的确它那动人的身姿使人一见倾心。 一月，水仙花开了!叶子翠绿翠绿，绿得发光，绿得 鲜亮，开着几朵洁白无瑕的小花，花中嵌着黄金般的花蕊，散出阵阵淡淡的幽香，显得格外高雅。水仙花与泥土无缘，雨花
石是它的“土壤”。水仙花的根部像只大洋葱，根下长着白色的根须。冬天，很多花儿都经不住严寒的摧残，受不了命运的考验——枯萎了。而水仙花却毫不畏惧，当室外寒风凛冽、冰天雪地的时候，它傲然挺立着，还是那么精神抖擞、生机盎然，仿佛在与寒风搏斗。 我爱水仙!爱它的美丽芬芳，爱它的高尚纯洁，更爱 它的顽强不屈! 秋天 秋天带着一身金黄，迈着轻盈的脚步，悄悄地来到了人间。 秋天的花很漂亮。月季红艳艳的花枝头昂首怒放，简直像一团燃烧的火焰。小草渐渐地变黄了，变成了金色的海洋。 秋天是丰收的季节。果园的果子都成熟了。硕大的苹果像捉迷藏的孩子露出了笑脸。熟透了的柿子软软的，放在嘴边一吸，从嘴角一直甜到心里。山楂红透了，像棵棵红宝石挂满一树。猕猴桃肉质鲜美，细腻柔软，又酸又甜，好吃极了。小麦长出了嫩芽，稻谷飘香。一棵棵的小白菜，映着朝晖，秋天是金色的季节，丰收的季节，美丽的季节，五彩缤纷的季节，它代表着繁荣和富强，我非常喜欢秋天，愿秋色永驻人间! 三年级暑假读后感 读《回乡偶书》有感 贺知章写的《回乡偶书》：少小离家老大回，乡音无改鬓毛衰。儿童相见不相时，笑问客从何处来。 这首诗说的是，有一个人小时候就离开了家乡，回来时已是满头白发了，只有家乡的口音没有多大改变。家乡的孩子都不认识他了，问他：“老人家您是从什么地方来的?”诗 人表达的是事过境迁、物是人非，唯一不变的是对家乡的热爱。
辞职报告范文简单版 辞职报告范文简单版 【范文一】 尊敬的****单位领导: 您好! 首先致以我深深地歉意,怀着及其复杂而愧疚的心情我写下这份辞职信,很遗憾自己在这个时候突然向***单位提出辞职,纯粹是出于个人的原因(家庭原因/身体原因等等),不能在***单位继续发展!离开这个单位,离开这些曾经同甘共苦的同事,确实很舍不得,舍不得同事之间的那片真诚和友善。但是我还是要决定离开了,我恳请单位原谅我的离开,批准我辞职。 同时,很荣幸曾身为***单位的一员,能有机会在这里工作学习,不胜感激!衷心祝愿所有在****辛勤工作的员工工作顺利,事业有成! 此致 敬礼 辞职人, xxx 时间, 年月日 (注,应在正式离职前三十天提交辞职报告) 【范文二】 领导, 您好! 感谢公司多年来对我的培养关心和照顾,从XX年5月份来到xx公司至今,我学到了很多东西,今后无论走向哪里,从事什么,这段经历都是一笔宝贵的财富,我为在网通公司的这段工作经历而自豪。 而今,由于个人原因提出辞职,望领导批准。 此致
敬礼 辞职人, xxx 时间, 年月日 【范文三】 尊敬的xx主任, 您好! 工作近四年来,发现自己在工作、生活中,所学知识还有很多欠缺,已经不能适应社会发展的需要,因此渴望回到校园,继续深造。经过慎重考虑之后,特此提出申请,我自愿申请辞去在xxx的一切职务,敬请批准。 在xxx近四年的时间里,我有幸得到了单位历届领导及同事们的倾心指导及热情帮助。工作上,我学到了许多宝贵的科研经验和实践技能,对科研工作有了大致的了解。生活上,得到各级领导与同事们的关照与帮助;思想上,得到领导与同事们的指导与帮助,有了更成熟与深刻的人生观。这近 四年多的工作经验将是我今后学习工作中的第一笔宝贵的财富。 在这里,特别感谢yyy(xxx的上级单位)a主任、b主任、c主任在过去的工作、生活中给予的大力扶持与帮助。尤其感谢xx主任在公司近二年来的关照、指导以及对我的信任和在人生道路上对我的指引。感谢所有给予过我帮助的同事们。 望领导批准我的申请,并请协助办理相关离职手续,在正式离开之前我将认真继续做好目前的每一项工作。 祝您身体健康,事业顺心。并祝yyy、xxx事业蓬勃发展。 辞职人, 【范文四】 尊敬的xx:
小学三年级日记100字小学三年级春节日记范文三篇 篇一 今天晚上最著名的就数春节欢晚会，当时钟才转到七点三十五时，我便迫不及待的打开电视，爬进被窝。终于开始了，听说今年的导演是冯小刚，风格肯定和往日不同，被人亲切的称为冯氏春晚。看到一半，瞌睡虫便朝我爬来。不过我却对一些节目流连忘返，冯巩的送礼最让我印象深刻，在笑声与开心的背后，却告诉人一个深刻的道理，也反应了社会的黑暗，与领导的清廉，当然最重要的还是孝顺，这毕竟是中国流传千年的文化。还有乐于助人的风气表演小品、各个名族舞蹈与歌曲、法中50周年纪念日(法中歌手合唱)、韩国帅哥和中国歌手合唱.......虽然我只看了一半，但我已被那千姿百态的节目吸引了。 篇二 为什么说春节是快乐的呢?这都是因为除夕那天晚上放烟花。 除夕那天晚上我和爸爸去放烟花。我左手拿着冲天炮、右手拿着震天响、脖子夹着降财伞，和爸爸下了楼。
我先点燃了冲天炮，啪、啪、啪、啪、啪，这五响形成了一条龙和龙年快乐四个字，我大声喊道：“xx万岁!” 接着，我点燃了震天响，“轰”的一声巨响，把我吓的胆战心惊。我想：“这声音可能跟沉香救母时，劈开华山的声音一样大。” 然后我点燃降财伞，只听“嘭”的一声，一个带金元宝的降落伞掉到了我的头上。“哈哈，我变成小富翁了，耶!” 最后我回到家吃年夜饭，汤圆又香又甜，粘粘的，味道好极了，我最爱吃了! 我爱过春节，春节美好又快乐! 篇三 今天吃晚饭之前，我跟妹妹和弟弟说：“吃饱饭以后放鞭炮吧，放那个窜花的!”妹妹和弟弟听了异口同声、兴高采烈地说：“好啊!好啊!”
吃饱饭以后，我就向爸爸借了个打火机，拿了个鞭炮就出去了。我一看说明：不能手持。妹妹和弟弟都犯浑了：不能手持那怎么放啊?我灵机一动：昨天晚上放了个冲天炮啊!把这个鞭炮插在那里面。 好了，准备就绪!我说：“放!!!! 一放我们才明白：原来不是五颜六色的而是一个颜色的，不过也挺好看的! 以后我还要放鞭炮! 内容仅供参考
辞职报告范文简单版 辞职报告有时候不需要写的很复杂，简单明了的辞职报告少了很多程序和理由，也能让人清晰了解你的辞职原因。以下就是辞职报告栏目为您提供的范文几篇，供您参考! 辞职报告范文简单版 【范文一】 尊敬的****单位领导: 您好! 首先致以我深深地歉意，怀着及其复杂而愧疚的心情我写下这份辞职信，很遗憾自己在这个时候突然向***单位提出辞职，纯粹是出于个人的原因(家庭原因/身体原因等等)，不能在***单位继续发展!
离开这个单位，离开这些曾经同甘共苦的同事，确实很舍不得，舍不得同事之间的那片真诚和友善。但是我还是要决定离开了，我恳请单位原谅我的离开，批准我辞职。 同时，很荣幸曾身为***单位的一员，能有机会在这里工作学习，不胜感激!衷心祝愿所有在****辛勤工作的员工工作顺利，事业有成! 此致 敬礼 辞职人：XXX 时间：年月日 (注，应在正式离职前三十天提交辞职报告)
【范文二】 领导： 您好! 感谢公司多年来对我的培养关心和照顾，从20XX年5月份来到xx公司至今，我学到了很多东西，今后无论走向哪里，从事什么，这段经历都是一笔宝贵的财富，我为在网通公司的这段工作经历而自豪。 而今，由于个人原因提出辞职，望领导批准。 此致
敬礼 辞职人：XXX 时间：年月日 【范文三】 尊敬的xx主任： 您好! 工作近四年来，发现自己在工作、生活中，所学知识还有很多欠缺，已经不能适应社会发展的需要，因此渴望回到校园，继续深造。经过慎重考虑之后，特此提出申请：我自愿申请辞去在XXX的一切
职务，敬请批准。 在XXX近四年的时间里，我有幸得到了单位历届领导及同事们的倾心指导及热情帮助。工作上，我学到了许多宝贵的科研经验和实践技能，对科研工作有了大致的了解。生活上，得到各级领导与同事们的关照与帮助;思想上，得到领导与同事们的指导与帮助，有了更成熟与深刻的人生观。这近四年多的工作经验将是我今后学习工作中的第一笔宝贵的财富。 在这里，特别感谢YYY(XXX的上级单位)A主任、B主任、C 主任在过去的工作、生活中给予的大力扶持与帮助。尤其感谢xx主任在公司近二年来的关照、指导以及对我的信任和在人生道路上对我的指引。感谢所有给予过我帮助的同事们。 望领导批准我的申请，并请协助办理相关离职手续，在正式离开之前我将认真继续做好目前的每一项工作。 祝您身体健康，事业顺心。并祝YYY、XXX事业蓬勃发展。
【个人简历范文】 申请意思是向上级说明理由，提出请求，有关向政府申请内容，欢迎大家一起来借鉴一下！ 向政府申请书格式范文一 县人民政府 在县委、县府的领导和指挥下，在相关部门的大力支持下，县蚕丝公司、蚕种场的破产改制工作有序进行，现已进入人员安置阶段。 县蚕丝公司各类人员522人，其中在编正式职工408人，退休人员48人，退养蚕桑辅导24人，在岗蚕桑辅导员24人，长期临工4人，遗属定补人员4人。 按照批准的人员安置方案，根据债权、债务清算报告，经测算，人员安置费用6428万元，退付集资款162万元，支付兑发工资3185万元，共需资金11173万元。 因非整合资产的处置(已委托国土供应中心)尚需时日，按照县委、县府的安排布署，为了确保在今年6月底前破产终结，故特请示县政府先在县财政借支1000万元资金用于安置职工，待资产变现后再与县财政算帐。 以上请示可否，请批示。 日期 向政府申请书格式范文二 县财政局 年初以来，我们XXXX党委、镇政府为完成县委、县政府安排部署的各项重点工作任务，开展了大量工作，开局良好。 特别是今春气候倒春寒现象严重，持续雨雪灾害天气，造成农民不能及时种地，为帮助农民挖沟排涝、抢种春播以及解决特困户种地困难等，占用了一定资金，造成我镇目前办公经费十分紧张。 为保证机关正常运转，更好地完成全年各项工作任务，特申请财政局提前预拨经费10万元，解决我镇资金短缺困难。 特此请示，批准为盼。 XXXX人民政府
20XX年5月14日 向政府申请书格式范文三 xx人民政府 xx旅游地产暨现代农业建设项目是由(陕西xx集团)下属陕西xx房地产开发有限公司与xx房地产开发有限公司共同投资，根据《汉中市保护利用总体规划》，本着保护性利用自然资源的原则，在兼顾环境效益，合理的利用生态资源，统筹城乡发展的基础上，力图打造的一个具有养生体验功能的高科技集旅游地产和现代农业示范区有机整合的地方发展项目。 一、xx旅游地产暨现代农业建设项目简介 xx旅游地产暨现代农业建设项目，将充分运用“文化传承、产品核心竞争力、价值附着”三大策略、“传统农业、现代农业、未来农业”三大板块、“互惠、分享、共赢”三大原则，进行整体规划。项目规划将综合考虑国家及汉中生态保护相关政策，把协调发展“三农问题”作为根本的出发点。项目结合项目地良好的自然环境、当前现代农业的发展契机、西北地区休闲市场巨大需求，结合项目单位自身的人才、技术、管理、资金等资源等优势条件，利用农业为主线的链条式发展，以高端科技农业为主打，以规模特色农业为品牌，以休闲体验旅游为提高，把农业和旅游产业有机结合。建设国内外先进农业技术的引进转化示范区、农业专家课题示范区和自驾旅游集散中心。带动旅游观光、生态体验、餐饮住宿等辐射经济效益的升级。体现休闲自然的生活态度和生活方式，成为全国性的农业科技示范教育基地。实现第一产业、第二产业和第三产业的联动、互利和产业链升级发展。 xx项目以农业发展为基础，休闲养生体验为主题，旅游产业为拓展。项目实施后，将积极促进和改善xx区域的生态环境,打造优质生态宜居游乐生活，增进居民幸福度和营造社会和谐度。 项目总投入约12亿，项目直接收益较高，可带来超过2亿的税收和6亿的衍生收益，并能解决农村剩余劳动力2000以上，可为这些劳动力带来每年2万元以上的收入，给武乡区域带来极大的综合效益。 二、项目投资单位简介 本项目投资单位陕西xx房地产开发有限公司;具体实施单位xx房地产开发有限公司;两公司均为陕西xx集团全资下属单位。 陕西xx集团是经由区政府领导、经贸局和xx房地产开发有限公司共同努力引入汉中，并成功注资落户的外来企业。 陕西xx集团，是以煤炭、电力为主导产业，以资源综合开发利用为宗旨，坚持节能环保发展观的新型能源企业。该公司先后被榆林市委、市人民政府授予“榆林市十佳企业”、“榆林市非公有制纳税十强企业”、“挂牌重点保护企业”等荣誉称号，被榆林市工商局授予“重合同、守信用”单位，被神府经济开发区评为“先进企业”，被省农行授予“AAA级企业”称
【篇三】小学三年级日记200字范文 今天，妈妈去加班，我做完作业没什么可干，见家里的地板很脏，就拿起笤帚扫起了地。我先从阳台上扫起，从里到外，仔仔细细地把每一个角落都扫得干干净净。扫完地看时间还早，就趁着高兴找来拖把准备拖地。我学着妈妈的样子，先把拖把放入水中泡一会儿，洗净，使劲拧干，就认认真真地拖了起来。妈妈回到家，看到我的劳动成果，特别高兴，说：“以后你每做一件家务事，妈妈就给你一块钱，给你买学习用品。”我特别高兴，心想：通过自己的劳动得来的工资一定很特别，因为它们是用自己的汗水换来的，有一种特别的意义。现在，我的钱包里已经攒下了2元钱，虽然不是很多，但我却倍加珍惜，因为，那是我的第一份劳动收入。 【篇四】小学三年级日记200字范文 上午，我和老爸去上街，正好遇到了红灯，我们只好停了下来。这时，我看见一位老奶奶在路边卖老母鸡。她把鸡的两只脚紧紧的捆在一起摆在地上卖。突然，有一只鸡跳了起来，夸张的是它居然用绑着的那两只脚跳着跳过了马路。而老奶奶并没有察觉，看见大伙儿边说边笑，这才发现她的一只鸡已经跑了，她连忙起身过了马路去抓鸡了。我见了这一幕，我忍不住哈哈大笑起来。 这鸡太厉害了，两条腿腿都被绑起来了，竟然还可以独脚跳着过马路。究竟是什么力量让它变得如此勇敢呢？我猜想它肯定是为了逃命。老奶奶为了追鸡跑的气喘吁吁，一定很生气，因为她想呀鸡脚都绑得紧紧，还差点让它给跑了。 这一幕确实很搞笑，我想对鸡说：“我很同情你，但没有办法，因为你是一道美味的菜哦！ 【篇五】小学三年级日记200字范文 包饺子是中国的传统饮食习俗，更是一种重要的文化习俗，无论在北方还是南方，我们都爱包饺子、更爱吃饺子，特别是在北方过春节的时候，那可少不了它啦！ 饺子馅香，皮儿韧，说起来好吃，做起可难啦，先说和面吧，先要将上好的精面反复的搓揉，直到很有韧性才行，再将它搓成一条条的圆柱状，再用刀把它搓成一小团一小团的，然后再拿擀面杖将它压成扁扁的，最后再在上面撒上一层干面粉，这样，皮儿就做成啦！ 再说说做馅儿的吧，做馅可以做猪肉馅、牛肉馅、羊肉馅、也可以做蟹肉馅，还可以做成素菜馅、豆腐馅等等，里面还可以夹上葱子、韭菜什么的，切得细细柔柔的馅儿被皮儿包起来，咬在嘴里不用说有多好吃呢！做好的饺子可以蒸、可以煮、还可以油炸，那可是好吃极啦！ 还有的人喜欢在过年的时候在一大堆饺子里挑一个出来，拿一枚硬币包进馅儿里去，如果有谁吃到了这一个特殊的饺子，那就表示这个人很幸运、很有福气，会有一年的好运气在等着他呢（她）！这时候，满桌子吃饺子的人都会惊喜地叫起来，过年的气氛就会更欢快、热闹啦！ 啊，饺子，饺子，中华民族的传统饮食，我们都爱吃你，美味的饺子！ 【篇六】小学三年级日记200字范文 今天是大年三十，家家户户每个人的脸上都洋溢着喜庆。有的人忙着在贴春联，有的人忙着准备年夜饭，还有的人忙着挂大红灯笼…最热闹的就要数年三十的晚上。 我们一家人吃完年夜饭，就开始着手准备放鞭炮，烟花。美丽的烟花在天空中绽放，好像对我说新年快乐。放完鞭炮，我就开始放孔明灯。孔明灯是在三国时期诸葛亮发明的，那时候诸葛亮用他来传递信息的。 先打开塑料袋，把孔明灯小心翼翼的展开，不弄把它弄破，要不然就会漏气会让他飞不起来的，然后把一块蜡固定在孔明灯内部的铁丝上，接着再让老爸用打火机把蜡点燃，蜡是正方形的点火的时候把正方形的对角点燃，在蜡点燃的同时再让妈妈和爸爸小心翼翼的拎起孔明灯的上方两只角，把它拎在半空中，火一点点在燃烧，孔明灯渐渐的膨胀起来，然后手端起孔明灯下端的园环上，慢慢的抬高孔明灯，逐渐放开手，孔明灯就飞上天去了，孔明灯慢慢慢慢的飞向天空，飞向远空在黑夜中就像一颗小星星。 对着孔明灯许下我的心愿：希望在新的一年家人健康幸福。
简单辞职报告范文50字左右一份简单的辞职报告应该怎么写呢下面小编跟大家分享几篇简单辞职报告范文，以供参考! 简单辞职报告范文一尊敬的领导您好： 我进**已经有几个月了，由于我个人的原因。经过深思熟虑地考虑，我决定辞去我目前在公司所担任的职位。 我非常重视在**公司内这段经历，也很荣幸成为**的一员，特别是**的处事风范及素质使我倍感钦佩。在**这几个月所学到的知识也是我一生宝贵的财富。也祝所有**成员在工作和活动中取得更大的成绩及收益! 望领导批准我的辞职申请，并请协助办理相关离职手续(本人在2**年*月*日离职)。在正式离开之前我将认真继续做好目前的每一项工作。 愿祝**生意兴隆! 敬请领导同意并批复! 辞职人：xxx 20 xx年x月x日 简单辞职报告范文二尊敬的公司领导： 我很遗憾在这个时候向公司提出辞职，我来公司也3个多月了，对公司以人为本体恤下属特别是对我们基层监管员的照顾让我颇为感动，让我一度有着找到了依靠的感觉，而今公司正值用人之际，业务发展迅速，但是由于个人方面的
一些问题，本人确实是不得已而为之，由此给公司带来的不便还望能够谅解!我考虑在此辞呈递交之后的两周内离开公司，这样您将有时间寻找合适人选来填补因我离职而造成的空缺，同时我也能够协助您对新人进行入职培训，使他尽快熟悉工作。能为公司效力的日子不多了，我一定会站好自己最后一班岗，与新人做好交接工作，尽力让项目做到平稳过渡! 我很遗憾不能再为公司辉煌的明天贡献自己的力量，我只有由衷的祝愿公司业绩一路飙升! 此致 敬礼 辞职人：xxx 20 xx年x月x日 简单辞职报告范文三尊敬的领导： 我很遗憾自己在这个时候向公司正式提出辞职申请。 来到公司也已经快两年了，在这近两年里，得到了公司各位同事的多方帮助，我非常感谢公司各位同事。正是在这里我有过欢笑，也有过泪水，更有过收获。公司平等的人际关系和开明的工作作风，一度让我有着找到了依靠的感觉，在这里我能开心的工作，开心的学习。或许这真是对的，由此我开始了思索，认真的思考。 但是最近我感觉到自己不适合做这份工作，同时也想换
向政府申请报告范文 【篇一：写给市政府的项目请示】 入近20万经费，历时半年，对 征地200～300亩，设计招生3000～4000人。目前一期资金 已经筹措完毕，随时可以到位进入征地程序。建设工期预计一 年时间，全部基建完成后，预计2012年下半学期即可实现新生 入学。一期工程时间预计在2011年5月～2012年1月，预计 投资6000～8000万元人民币；二期工程时间预计在2012年 2月～2012年6月，预计投资5000万元人民币。 教师的培训和指导，并有管理人员长期入驻本校监督管理。为 我们的要求是：政策上的优惠；土地价格的优惠；协调有关部门加 快我们的工作进度。 恳请尽快答复！ 项目联系人： 2010年4月7日 【篇二：土地用地申请报告范文】 土地用地申请报告范文申请人：胡xxx 住所地：xx省xx市xxx村 法定代表人：胡xx 申请事项：申请人因建养鸡场需要，特此依法向宝丰县人民政府申 请养殖用地30亩。 事实与理由： 申请人是已毕业的大学生，大学期间通过自学与实践掌握了一定的 养殖知识与技能，形成了自己的养殖理论体系，并决定开办自己的 养殖场，同时带动本村村民一起走发家致富的道路。特向宝丰县人 民政府申请土地建立一座存栏量为一万只的肉鸡养殖场，建设完毕 后可以向本村村民提供工作岗位，提高部分村民的经济收入。在政 府的支持与引导下，通过自己坚持不懈的努力与奋斗，逐步扩大养 殖规模，建立养殖小区，采取基地加农户、包回收的模式进行运作，从而实现养殖、销售一条龙服务，带动本村乃至本乡养殖业的发展，实现共同富裕。现根据《畜牧业法》、《中华人民共和国土地承包法》、《中华人民共和国土地管理法》及《中华人民共和国土地使
例文1： 9月4日星期五晴 今天放学回到家，妈妈拿着一张培训中心发的广告纸，一边看一边用商量的口气对我说；王臻啊，你报一个作文辅导班吧。 我马上问：为什么？ 你已经升入三年级了，作文很重要，跟专业的老师学学，对你提高写作很有好处的。 我想了想，不行，好不容易放假还不让我休息，我义正词严地拒绝了。 妈妈显然不高兴了，你怎么这么不求上进？ 于是一场争论开始了 我抢着说：这样的话，学校还不如不放假呢。你不能剥夺我的休息时间。 妈妈说：就星期六上半天。 我仍然理直气壮：你怎么知道是专业的老师，难道比我们学校的老师还专业？我只要认真听老师讲课，多看优秀的作文，我相信我会写好的。 妈妈见我态度坚决，拿我没辙，就说：明天写一篇作文，如过写的好就不用上，写不出来的话，没有商量的余地，必须要去。 我信心十足的对妈妈说我一定会写好的。为了我的休息时间，我要努力。 例文2 10月14日星期四天气：雨 今天，老师给我们布置了一项作业：在家种绿豆，写观察日记。 晚上，我让妈妈抓了一把绿豆给我，绿豆身上绿绿的，个子小小的，硬硬的。按妈妈的要求，我拿来一个杯子，把绿豆放进去，再加上一点儿水。 10月15日星期五天气：晴 放学回家，我迫不及待地跑到厨房去观察绿豆，我发现喝饱了水的绿豆变大了，肚子涨得圆鼓鼓的。于是，我又按着妈妈的要求，把浸泡了一天的绿豆水倒掉，并把绿豆放在一个塑料碗盖上，还铺上一块大小相同的湿纱布。 10月16日星期六天气：晴 今天一大早，我正做着美梦。妈妈风风火火地来到我的房间摇醒了我，兴奋地说：快去看看我们种的绿豆，它们。。没等妈妈说完，我像弹簧似的，立刻从床上一跃而起，匆忙地穿好衣服，飞快地奔向厨房。我仔细观察，惊喜地发现有一些绿豆裂了一道口子，还有一些绿豆已经发芽了。这些小芽尖尖的、白白的，像一个个问号，可爱极了！ 例文3 10月1日星期六天气：晴 晚上我嚷着要吃梨，而且还是蒸梨。妈妈说：那好，不过你得一起做。我直爽地答应了。 我们先把梨洗得干干净净，然后在梨上面切一刀，切下来就象一个圆圆的小雨伞，再把梨的中间掏空，再放一些冰糖，再把圆圆的小盖子盖上，放到碗里，然后放到煤气上蒸了二十分钟。妈妈端出梨，我就想吃，可是太烫，妈妈吹了吹，等了一会儿，我尝了尝：哇，真甜呀！于是大口大口地吃起来，可我吃了半个，就不想吃了，喝了点水，我告诉妈妈明天我还要吃。 例文4 2017年8月3日晴
[简洁版辞职报告]辞职报告范文简单版 首先，非常感谢您这x年来对我的信任和关照。 这段时间，我认真回顾了这x年来的工作情况，觉得来xxxx公司工作是我的幸运，我一直非常珍惜这份工作，这一年多来xxxx公司领导对我的关心和教导，同事们对我的帮助让我感激不尽。 由于我状态不佳，和一些个人原因的影响，无法为公司做出相应的贡献，自已心里也不能承受现在这样坐在公司却无所作为，因此准备辞职。 感谢诸位在我在公司期间给予我的信任和支持，并祝所有同事和朋友们在工作和活动中取得更大的成绩和收益! 此致 敬礼! 辞职人：xxx 20xx年xx月xx日
简洁版辞职报告(二) 尊敬的组长、班长、部门经理、人事部经理： 你们好，我将于30日后离职，与公司解除劳动关系，依据中华人民 __劳动合同法第四章第三十七条，现正式予以告知，请尽快安排人员交接相关工作。 此致 敬礼! 辞职人：xxx 20xx年xx月xx日 简洁版辞职报告(三) 尊敬的xx： 我很遗憾自己在这个时候向公司正式提出辞职。因为个人原因，我不能继续为公司工作下去了。
本着对公司负责的态度，我郑重向公司提出辞职。衷心祝愿公司业绩节节高升!公司领导及各位同事工作顺利! 此致 敬礼! 辞职人：xxx 20xx年xx月xx日 简洁版辞职报告(四) 尊敬的公司领导： 您好!工作近四年来，发现自己在工作、生活中，所学知识还有很多欠缺，已经不能适应社会发展的需要，因此渴望回到校园，继续深造。经过慎重考虑之后，我决定辞职，请领导谅解! 此致
敬礼! 辞职人：xxx 20xx年xx月xx日 简洁版辞职报告(五) 尊敬的领导： 您好! 我因为诸多个人原因，经过深刻冷静的思考后，郑重的向公司高层提出辞职要求。 首先，在贵公司工作的这几个月以来，我收获良多，在领导以及同事的帮助下使我掌握了很多非本专业的知识，开阔了眼界，增长了阅历。 其次，公司的工作气氛很好，同事们工作都很努力，领导也很体谅下属。使我在公司感受到了家的温暖。
【篇一】小学三年级日记200字范文 星期四，妈妈带我去牙防所补牙。我很害怕！还出了一手的冷汗呢！ 到医院开始补牙了。医生让我躺在床上，可我一边躺着一边情不自禁地哭了。妈妈见了，连忙说：“不怕，不怕，不疼的”。但是我还在轻轻地哭。医生戴起头套，穿上手套，拿出放大镜，开始看我的牙齿。看了一会儿，医生皱起了眉，转身对妈妈说：“你家女儿的那颗蛀牙蛀得很厉害，也许保不住了。现在只能试试看可不可以。”医生开始认真细心地补着。医生用钩子抠我牙齿的那一刻，我真希望变成妈妈，妈妈变成我呀！不过，我又想早知现在，又何必当初呢！当我在考虑这些问题时，时间一分一秒地过去，疼痛也在一分一秒地消失。终于，牙齿保住了。我，妈妈和医生都放心地笑了。 我在回家的路上心想：嗨！真后悔以前多吃糖，不好好地刷牙啊！从今以后，我一定要好好保护我。 【篇二】小学三年级日记200字范文 秋天来了，天气变得凉爽了，不像夏天那么热了。许多女孩把裙子脱掉了，换上了漂亮的衬衫。 大雁摇动着翅膀，一路欢歌笑语地飞向温暖的南方。小燕子在天空中转了几圈，依依不舍地也飞向了南方。 火红的枫叶、金黄的柳叶和杨树叶，像五颜六色的蝴蝶在空中旋转飞舞。秋姑娘把绿油油的小草织成金黄的地毯。 红艳艳的大苹果大得压弯了枝头。像宝葫芦似的大鸭梨挂满了枝头。一串串晶莹剔透的大葡萄和小灯笼似的樱桃让人垂涎欲滴。 庄稼地里金黄的稻谷笑弯了腰。火红火红的高粱醉红了脸。金黄的玉米乐开了怀。 秋天是一个丰收的季节，秋天是一个硕果累累的季节，秋天是一个收获的季节。 秋天真美呀！我喜欢秋天。 孙昊然作文辅导班马老师的评语：真棒！写出了秋天的美！用词生动、形象。 【篇三】小学三年级日记200字范文 今天，妈妈去加班，我做完作业没什么可干，见家里的地板很脏，就拿起笤帚扫起了地。我先从阳台上扫起，从里到外，仔仔细细地把每一个角落都扫得干
企业向政府申请书范文 ******建设局： 为了更好的贯彻落实国家对资源综合利用的指导思想，促进合理的节约资源，提高资源利用率，保护环境实现经济社会的可持续发展的战略方针。************有限责任公司顺应形势发展，准备在******投资建设一条具有轻质、阻燃、保温、抗震性强并具有可持续发展的轻集料小型空心砌块建筑材料生产线。此项目的投资建设能达到节约能源、保护土地、变废为宝及综合治理环境污染的目的。 投资建设此项目我公司具有以下优势： 一、轻集料小型空心砌块是以矿渣、炉渣、粉煤灰加有石硝为骨料，? 以水泥为胶结料，被广泛使用于工业与民用建筑的非承重砌块、承重砌块、保温块。是一种节能、节土、利废的可持续发展的建筑材料。该产品生产工艺无二次污染产生，市场前景广阔变废为宝，造福后代并具有极高的社会效益和环境效益。而我公司经营煤矿及煤炭销售多年，常年与矿渣、粉煤灰、水泥等物接触。 二、我公司为******热力公司供运供热用煤已有多年，合作非常融洽。随着******城市建设规模的不断扩大，******热力公司现
在每年冬季供热用煤需要4万多吨，为了保证冬季的正常供暖，秋季储存煤就非常关键，但是热力公司的场地有限，无法大量储存煤，加之供热产生的炉渣占地面积也很大。为此双方约定由我公司申请30亩土地，其中一半无偿作为热力公司储煤场地，一半用于我公司建设轻集料小型空心砌块生产线使用，同时供热产生的炉渣及时运送到本厂作为生产原料。充分体现了双方互利互惠的原则。 综上所述，建设轻集料小型空心砌块生产线，即符合国家产业政策，同时为确保******冬季正常供暖，热力公司秋季储煤的问题也得到了解决。因此，恳请******建设局审批30亩土地作为 ************有限责任公司建设轻集料小型空心砌块生产线和******热力公司储煤场地为盼。 ************有限责任公司 2011年? 月? 日
小学三年级日记范文四篇 【篇一】小学三年级日记范文 今天是合唱比赛，先是四班上场。他们排着长龙似的队伍来到了舞台。他们的衣服一模一样，都像双胞胎一样。他们站的纹丝不动，像松树一样直，时不时露出了微笑，他们放出了像百灵鸟一样的歌声，多好听啊！ 看，该我们上场了，我的心理就想揣了两只小白兔，心里在默默的想：我会不会在唱的时候唱错了呀，还有我害怕会不会在摇头的时候摇错了，还怕我在唱的时候会乱动，可是当我一走上去，看到老师们微笑着，用那种鼓励的眼神看着我们，我一下就不紧张了，放松了好多，很轻松的就唱了下来。我希望明年还能参加。【篇二】小学三年级日记范文今天是过年，我非常开心。 我们首先是到外婆家去拜年，一路上，我看着大街上没有以前的大街热闹，为什么呢？妈妈说过年所有人都要去拜年，所以所有的店面都没有开，到了外婆家后，外婆一看到我连忙从口袋中拿出红包，递给了我，妈妈对外婆说；“这么大了还要红包，不要，你拿走自己用吧！”可是我非常想要红包，因为拿这些钱可以买自己想要的东西，所有我很贪心的拿下这个红包。 过年不是仅仅拿红包的节日，也是放烟花爆竹的节日。 在吃饭之前，我们把爆竹放好，我可是大胆到自己去放，我放了后看到线着火了，我连忙跑，只听见“啪啪啪啪”的声音，我非常喜欢闻烟花的味道，也不知道为什么，放好后
就去闻闻，后来，我们一起开心的吃起饭来了。 啊！过年多么的好！我爱过年！【篇三】小学三年级日记范文 昨天我说今天还要去外婆哪儿的体育设施哪儿玩儿，但是不玩单杠，也不玩儿秋千，我玩跷跷板。 我刚刚睡醒，就想起今天还要去玩跷跷板，就赶紧起来了。我早饭也顾不上吃，就催妈妈带我去玩儿跷跷板，我没有吃完饭，妈妈哪里肯带我去呀？妈妈说我得先吃完饭，我只扒了几口饭就催妈妈赶快去，妈妈看我吃饭了，就带我去了。我和弟弟做上跷跷板以后，我们两个互不相让，一会儿是我“战胜”弟弟，一会儿是弟弟“战胜”我。、要回家了，我求妈妈再让我玩儿一会儿，但妈妈不让。就算这样，这也是我最难忘的一个星期天，我永远不会忘了这个星期天。【篇四】小学三年级日记范文 昨天吃过晚饭，爸爸妈妈带我回奶奶家玩。一到那里，我正准备打开电视，就听见奶奶说：“党嘉悦现在长大了，让她去学拉二胡吧。”爸爸妈妈一听就同意了，奶奶说先给我问问老师，我听了心里也很感兴趣，急着想看看二胡是什么样的。 今天中午，奶奶就打电话让我去见老师，在那里老师让我跟着他打节拍，又看了看我的手，说我还不错，挺适合学二胡，我听了也很高兴，心里暗下决心要好好学。 下午我就去老师那里听了一节课，老师给我讲怎样拿二胡，给我讲最简单的乐理，还给我布置了作业，让我回家练
辞职报告简短版范文 《中华人民共和国劳动法》第24条明确规定：“当事人双方可以协商解除劳动合同”。这种“协商解除劳动合同”正常而便捷的方式就是递交辞职报告和批准辞职请求。以下是由为大家推荐的辞职报告简短版范文，欢迎大家学习参考。辞职报告简短版范文一 尊敬的邱总： 您好! 时光荏苒，不知不觉我来公司已经很长时间了。起初还梦想着成为一个成功的销售员，现在成为了幻影，确实让人沮丧。 本来我对销售充满了信心，但从三个月的不断学习和探索中我发现不论是我的性格、毅力、学识都达不到一个业务员的要求。三个月，没卖出去一台设备，这样的销售业绩着实令我无地自容。销售是以成败论英雄的，我们不愿面对努力付诸东流，可现实就是这样斩钉截铁。 现在我的工作兴趣锐减、工作态度消极。站在一个员工必须爱岗敬业的最基本的职业操守的立场上，我已经不能胜任这份工作。与其不负责任的尸位素餐，不如退位让贤。无论对公司还是我，我认为这都势在必行。 这三个月，我也有很大的收获，也许再踏出光越的大门
以后，我的这些电话联系客户的经历、学习关于设备知识的过程都没有了用武之地。但是我认为它们教会我的是交流的艺术和提高自己、竖立自信的重要手段，这些都将让我一生受用。 在这么长的时间里，没有给给公司带来任何利润，您也没有过于责备。这让我更加的惭愧。今天做出这样的决定，我觉得对您是一种深深的辜负。谢谢您在这段时间的提携和照顾。 在此也衷心的祝愿光越的发展势头能够如日中天、您能成为炙手可热的成功企业家。 望领导批准我的申请，并能协助我完成离职的相关手续。 此致 敬礼申请人：*** 20xx年xx月xx日辞职报告简短版范文二 尊敬的公司领导： 在递交这份辞呈时，我的心情十分沉重。现在公司的发展需要大家竭尽全力，由于我状态不佳，和一些个人原因的影响，无法为公司做出相应的贡献，自已心里也不能承受现在这样坐在公司却无所作为，因此请求允许离开。 当前公司正处于快速发展的阶段，同事都是斗志昂扬，壮志满怀，而我在这时候却因个人原因无法为公司分忧，实