材料工程外文翻译--Mg-9Al-1Zn合金的半固体挤压成型

Mg-Al系镁合金半固态坯料制备及触变挤压研究王迎;姜巨福;孙毅;曲建俊;杜之明;罗守靖【期刊名称】《特种铸造及有色合金》【年(卷),期】2009(0)11【摘要】采用拉伸试验机、金相显微镜和等径道角挤压等试验方法对Mg-Al系镁合金半固态坯料制备及触变挤压过程进行了研究。

结果表明,等径道角挤压工艺对Mg-Al系镁合金有很好的应变诱导效果。

经过等径道角挤压的Mg-Al系镁合金力学性能高,晶粒细小。

等径道角挤压+等温处理方法制备的Mg-Al系镁合金半固态坯的微观组织晶粒细小,球化程度高,微观组织非常均匀。

生产的AZ61、AZ80、AZ91D和AM60镁合金角框零件的微观组织细小,抗拉强度分别达到306.8、308.3、299.8、321.6MPa。

伸长率分别达到21.6%、28.4%、14.6%和29.6%。

【总页数】5页(P1019-1023)【关键词】等径道角挤压;Mg-Al系镁合金;半固态坯;触变挤压【作者】王迎;姜巨福;孙毅;曲建俊;杜之明;罗守靖【作者单位】哈尔滨工业大学机电工程学院;哈尔滨工业大学力学博士后流动站;哈尔滨工业大学材料科学与工程学院;哈尔滨工业大学机械工程博士后流动站【正文语种】中文【中图分类】TG249.2;TG146.22【相关文献】1.新SIMA制备坯料触变挤压AZ61镁合金零件的组织与性能 [J], 姜巨福;王迎;柳君;曲建俊;杜之明;罗守靖2.新SIMA制备坯料触变挤压AZ61镁合金零件的组织与性能（英文） [J], 姜巨福;王迎柳君＇，曲建俊2杜之明＇，罗守靖＇;王迎;柳君;曲建俊;杜之明;罗守靖;3.AZ61镁合金半固态触变挤压成形工艺研究 [J], 周冰锋;闫洪4.镁合金半固态触变成形用非枝晶组织坯料制备的研究进展 [J], 杨明波;胡红军;陈健;麻彦龙5.半固态挤压铸造镁合金坯料组织与性能研究 [J], 李东南;陈丁桂;范新凤因版权原因，仅展示原文概要，查看原文内容请购买。

中文翻译半固态挤压铸造工艺参数对AlSi9Mg连杆的显微组织以及力学性能的影响摘要:通过研究施加的压力，浇注和模具的温度的改变过程对连杆的半固态挤压铸造制备（SSSC）过程中的显微组织和力学性能的影响。

结果表明，非树枝状的初生α-Al颗粒均匀分布在整个连杆。

随着施加的挤压力的增加，铝颗粒尺寸减小而增大形状因子，从而增加连杆的力学性能。

当浇注温度和模具的温度增加时，原铝颗粒的大小和形状因子增加。

然而，如果模具温度高于300℃，形状系数突然下降。

在浇注温度575℃得到连杆SSSC过程中最好的显微组织和力学性能，模具约250℃温度，和100兆帕的压力。

1.简介半固态金属加工（SSM）是一个将传统的热锻造和铸造优势结合的技术。

它可以在近净形成型过程中形成的具有高质量的工件，这种技术已经被视为二十一世纪生产中最有前途的技术之一。

在SSM加工可以分为成形和流变成形。

由于在运输和自动化的方便，触变成形广泛用于汽车工业制造镁合金和铝合金。

除了获得非枝晶，小，近球形结构，触变成形的另一个重要特性是它的能力，它能较好地减少缺陷如缩松和液体分离。

高压压铸（HPDC）被广泛用于形成SSM，但很难完全消除孔隙由于其填充率高，导致湍流模腔填充和凝固收缩。

挤压铸造（SC）是一个通用的术语来表示一个制造技术在凝固过程是在高压下的推广，结合压铸的优点和锻造成一个单一的操作，液态金属在压力下凝固的应用。

这使生产部件有着高完整性和好的力学性能。

因此，半固态挤压铸造（SSSC），这可以被看作是半固态成形和挤压铸造的一个组合工艺，能够进一步提高产品性能。

挤压铸造工艺参数对铝合金、镁合金及其复合材料的组织性能的影响已进行了大量的研究。

近年来，应用SC在铝合金半固态加工的研究已在进行了。

Mao .等人研究了流变挤压铸造A356铝合金。

结果表明：当注射压力为22 MPa时，模腔不完全填充的然而，随着压力增加到34 MPa，腔可以完全填充和铸件表面质量很好。

半固态压铸件ADC12铝合金的可行性1。

采矿和材料工程专业,工程学院,大学Songkla王子2。

工业工程专业,工程学院, 科技大学Rajamangala Srivijaya3。

机械工程学系,工程学院,大学Songkla王子2010年5月13日至2010年6月25日文摘研究半固态压铸件ADC12铝合金的可行性。

已经确定活塞速度受壁厚和固态粒度缺陷的影响。

研究表明缺陷是由缩松引起的。

在实验中,采用的是半固态浆料制备半固态gas-induced(GISS)的技术。

然后,液态金属被转移到压铸模具之中,模具和套筒温度分别保持在180 C和250 C结果表明,GISS制作的压铸模具松孔较小没有气泡微观结构均匀。

实验结果表明并可以推论,GISS是可行的,适用于ADC12铝压铸过程。

另外GISS可以改进性能比如减少孔隙度和增加组织均匀性。

关键词:ADC12铝合金;半固态压铸;气体引起的半固态(GISS); 流变铸造第1章在电子、航天、和建筑领域。

多年来一直使用铝制部件这些部件通常使用高压压铸过程大量生产。

压铸过程的优点在于实现了如生产效率高和生产小且复杂的工件压铸过程包括将铝液在高压下注入到一个模具型腔中。

金属液灌到模具型腔中,导致金属反应和铸造的过程中产生气孔。

因此,最终的结构部分充满气泡和氧化物夹杂。

此外，压铸件通常不能进行加工,由于这些缺陷的产生要进行阳极氧化、焊接、热处理,[1-4]。

来提高的压铸过程质量和性能因此在这里介绍了半固态金属技术。

大量的半固态压铸的研究报道,使用半固态压铸有助于改善产品性能和提高质量的压铸零件[5-7]。

半固态金属加工过程使用流变路线可以提供更高粘度的液体与更高的粘度, 能够获得更少的湍流流动,这有助于减少空气孔隙度和氧化物夹杂在模具填充[5-7]。

此外,流变过程可以很容易被应用于传统的压铸模具的生产过程,只需要少量修改便可使效率提高[8]。

许多研究显示成功的半固态压铸与流变过程[7-12]。

半固态加工Al-Zn-Mg合金的组织演化
田文彤;罗守靖;路贵民
【期刊名称】《特种铸造及有色合金》
【年(卷),期】2002()1
【摘要】选用SIMA法制备的LC4合金及液相线凝固法制备的LC9合金为原料 ,
研究了半固态加工Al Zn Mg合金的组织演化。

由于这两种方法制备半固态坯料的机理完全不同 ,因此这两种材料加工后的组织演化规律截然不同 :LC4合金的晶粒
尺寸由于聚结而长大 ,而LC9合金的显微组织没有明显的变化。

借助于扫描电镜和能谱分析,对半固态加工前后的显微组织进行成分分析,结果表明晶界处由共晶区、低熔点的富Cu区和杂质区三部分组成 ,且LC9合金的再加热组织的液相薄膜厚度大于LC4合金的 ;半固态加工后制件各部分的成分基本一致。

【总页数】2页(P6-7)
【关键词】半固态加工;组织演化;层流
【作者】田文彤;罗守靖;路贵民
【作者单位】哈尔滨工业大学;东北大学
【正文语种】中文
【中图分类】TG249.9;TG135.1
【相关文献】
1.半固态7075铝合金浆料温度均匀化处理过程中的组织演化规律 [J], 杨斌;毛卫民;宋晓俊
2.Ti14合金半固态等温热处理过程中组织演化规律和晶粒长大行为 [J], 陈永楠;魏建锋;赵永庆;郑晶
3.半固态7075铝合金浆料温度均匀化处理过程中的组织演化规律 [J], 杨斌;毛卫民;宋晓俊;
4.Ti14合金半固态等温热处理过程中组织演化规律和晶粒长大行为 [J], 陈永楠;魏建锋;赵永庆;郑晶
5.铸造速度对Al-1.2Mg-0.7Si半固态合金组织演化影响的多尺度模拟 [J], 王娜;周志敏;路贵民;崔建忠
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半固态挤压铸造镁合金坯料组织与性能研究
李东南;陈丁桂;范新凤
【期刊名称】《特种铸造及有色合金》
【年(卷),期】2007(27)12
【摘要】采用双螺杆机械搅拌法制备半固态镁合金浆料,研究了半固态挤压铸造成形坯料不同部位的组织与性能。

结果表明,坯料组织中初生α相呈现不规则的多边形或蔷薇状结构,其晶粒平均直径为45～65μm。

坯料边缘和中心部位的组织结构明显不同,边缘处的组织更细小。

半固态挤压铸造成形工艺在提高铸件致密度的同时,也提高了铸件的硬度,与液态挤压铸造成形试样相比,其密度提高了0.33%,硬度提高了7.91%。

【总页数】3页(P930-932)
【关键词】半固态;镁合金;挤压铸造;组织;性能
【作者】李东南;陈丁桂;范新凤
【作者单位】福建工程学院材料科学与工程系
【正文语种】中文
【中图分类】TG146.22;TG249.2
【相关文献】
1.挤压铸造制备半固态AZ61镁合金的组织演变及力学性能 [J], 陈添;解志文;罗荘竹;杨钦;谭生;王赟姣;罗一旻
2.挤压铸造制备半固态AZ61镁合金的组织演变及力学性能(英文) [J], 陈添;解志
文;罗荘竹;杨钦;谭生;王赟姣;罗一旻;
3.AZ91D镁合金近液相线铸造半固态坯料的部分重熔 [J], 乐启炽;张新建;崔建忠;路贵民;欧鹏
4.半固态挤压铸造镁合金坯料组织与性能研究 [J], 李东南;陈丁桂;范新凤
5.Mg-Al系镁合金半固态坯料制备及触变挤压研究 [J], 王迎;姜巨福;孙毅;曲建俊;杜之明;罗守靖
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外文原文：The Ultimate Extrusion Scrap Remelt and Casting CenterPrepared by一Roger A. P．Fielding一BENCHMARKSGeorge E，Macey一Macey heat Transfer AssociatesD ．Hugh Barnard一Aluminium Industry ConsultingABSTRACT一Recent advances in scrap processing，melting，metal treatment, andcasting technologies have a major impact on the economics of recycling aluminumextrusion scrap. Technologies that permit rapid charging，melting，and melt preparation，are combined with processes that remove potential pollutants and particulates，refine themelt, and cast uniform ingot structures．The resulting facility is capable of producing a wide range of alloys and ingot sizes with minimum inventory levels while operating at high levels of productivity and energy efficiency. The facility is intrinsically safe to operate and meetsall current and near-term environmental standards．INTRODUCTIONThe Source of Aluminum Extrusion ScrapAluminum extrusion scrap comprises reject incoming log and billet, log and billet (and part-billets) rejected or damaged during or after the pre-heat furnace，part-billets and billets withdrawn from the extrusion press, butt ends of billet recovered from the press shear, and lumps of aluminum recovered from the extrusion die. After extrusion from the die, some scrap lengths-usually the front ends of the extrudate-are collected at the rough- cut saw, and some (in the same area of the press installation) as back-end samples．If there are significant differences in rod-length (the length of the extrudate emerging from multi-hole dies,）extruded scrap lengths must be collected from the press run-out table. Uneven extrusion lengths-which can still be seen in some extrusion operations-often have to be cut off at the stretcher tail stock; although some designs of stretcher allow for stretching with the excess length still in place．The excess extrudate known as stretcher scrap comprising front and back-ends of the extrudate which has been damaged at the stretcher, is removed at the finish-cut saw. Also removed arethe transverse weld from the extrusion of successive billets into a single length at the run-out, and the transverse weld allowance, which is much longer and must often be removed from the production of hollow extrusions.Although common alloy (AA6xxx) scrap generated at the extrusion press should be no more than 10 percent of the log or billet delivered to the extrusion press, it is not unusual to find that press scrap is closer to 25 percent due to a combination of the events listed above．If only because of the requirement to leave a larger butt (thereby ensuring that extrusions which might be subject to coring are not extruded)，the scrap generated when extruding medium and hard alloys will theoretically be greater than that from AA6xxx operations.From the above．it is evident that the scrap aluminum generated in a typical extrusion plant can be divided into five distinct families:1）The heavy logs and billet-each piece of which is the density of aluminum.2) Heavy butts which，because each is distorted during the shearing operation，are somewhat less den3) Extruded lengths, ranging from stretcher scrap to rejected full lengths, which，when bundled，are about 10 percent of theoretical density.se in bulk than the aluminum metal．4) Assorted pieces of extrusions, usually transported in boxes which，depending on where they are generated, can have a density of more than 10 percent.5) The saw chips-either loose or compressed into bricks of various sizes-which must be collected before the extrusion press at the log saw(s), or after the extrusion press at the rough-cut saw, where chips are deposited along the press run-out, at the finish-cut saw, and at any downstream cut-to-length or fabricating operationsThe Conversion of Aluminum Extrusion Scrap Into Prime IngotAluminum extrusion scrap is converted into prime ingot by melting，treating (cleaning), casting into logs，and homogenizing．The process itself generates additional scrap in the form of aluminum oxides (dross), liquid metal spills, metal trapped in filters, head and butt scrap, scrap logs, and saw chips.The cost of the conversion process is made up of the cost of the capital employed in the remelt and casting plant, the cost of metal lost (oxidized) during melting，the cost of the energy required in the melting process，the cost of alloy materials, the cost of all labor employed in the plant, the cost of the maintenance of furnaces and other production equipment, the cost of effluent treatment facilities (including the cost and treatment of water required in the casting process)，and the additional costs (over and above labor) of handling the aluminum and alloying materials in all their forms.Incomplete understanding of the remelt and casting process as it is applied to the scrap from aluminum extrusion operations，and the impact of the process equipment-and its operation on the cost of converting scrap to prime billet, results in an extraordinary range of conversion costs for what is actually a relatively simple operation．But it is not only conversion costs that suffer from lack of understanding of the processes and technologies involved．The quality of billet produced varies significantly between remelt and casting operations ostensibly designed to do the same job. And the environmental impact of the processes used range from the benign to the unacceptable.Establishing GoalsThe goal of the ultimate aluminum extrusion scrap remelt and casting center is to convert all forms of aluminum extrusion scrap to billet equivalent quality and prime (smelter) material at minimal total cost, with minimal impact on the environment.The Quality of Prime (Smelter) Billet. At the risk of stating the obvious: not all smelter-billet is created equal．Aluminum log cast from smelter metal contains impurities that affect the performance of the extruded product. The casting processes-which vary from smelter to smelter- can result in the production of cast structures which vary sufficiently such that they can be detected at the extrusion press．And，homogenizing facilities (and their operation），although ostensibly the same, also vary from smelter to smelter, again producing variations that can be detected at the extrusion press.Recycled aluminum scrap, or for that matter re-melted ingot originating at a smelter, can be processed in the ultimate remelt and casting center. This can be achieved at conversion costs that are lower than the traditional smelter premium to produce extrusion log and billet indistinguishable from prime-provided that alloy composition is maintained．Obviously, sorting and segregation of the incoming scrap feed-stock is essential if the quality of the remelted and cast product is to be maintained．Defining The IssuesThe issues affecting the efficient operation of an aluminum extrusion scrap remelt and casting center can be clearly stated as follows:1）Segregating mixed scrap2) Processing contaminated scrap3）Maximizing the recovery of metal units4) Maximizing energy (fuel) efficiency5) Maximizing product mix: alloy, compositiorand diameter6）Maximizing utilization of equipment7) Maximizing labor productivity8) Maintaining control of quality.Each of the issues can be aaaressea1)Separately as follows:1) Segregating Mixed Scrap. Scrap arisingthe remelt and casting center, which is limitedmetal recovered from dross, the occasionalog, the tops and tails of logs, saw chips anoff-composition material, is segregated and recvcled as appropriate．Scrap from extrusion plant "customers" is routinely segregated at the extrusion press and the finish-cut saw, as is the scrap arising in finishing and fabricating operations．Other aluminum scrap, which is priced lower than the mill scrap listed above because or its condition and dubious origin, must be sorted. Obviously, the purchase price will have retlectea the costs involved in sorting this scrap. Whatever can be recovered is added to those alloys havinghigher tolerance to compositional variation.＿．’balance must be downgraded，and rejected ror secondary uses．2)Processing Contaminated Scrap.Aluminum extrusion scrap can be contaminated with water and with oil，which is mixed with saw chips and is used to protect bright finishes；scrap can also be contaminated with paints and lacquers，thermal break materials, other plastics, rubber, and，in the case of fabricated components，with rivets and other fasteners made from many different materials. All these materials must be removed and/or separated from the aluminum before it is melted．Manv attempts have been made to process this contaminated material in the melting furnace, combining the processes of de-contamination, separation and melting．They have not been successful．The solutions include placing the contaminated material on an extended furnace hearth and allowing the contaminants to burn-off prior to charging．Another solution is to use dual or multi-chamber furnaces that contain，and attempt to re-circulate，the burning effluents to recover some of the energy released，adding it to that required to melt the scrap charge.While the capital cost of these solutions is high，the energy efficiency of each is relatively low. All require extensive effluent treatment facilities if they are to meet even the least stringent environmental regulations. This is because the large volumes of combustion products (and unburnt volatile materials), released at the instant the charge enters the furnace，are rapidly carried from the furnace towards the effluent treatment systems. Incinerators, coolers and bag-houses must be sized to accommodate the maximum flow rates.There is a better wayl Contaminated scrap can be treated continuously, before it is charged into the furnace，at instantaneous rates that are a fraction of the common charge rates. For example，an efficient furnace-charging system might be designed to load ten tons into the furnace in a matter of seconds: a rate of (say) 20 tons per minute. On the other hand，a system for continuouslytreating contaminated scrap for the same furnace will be required to treat scrap at a rate of (about) 200 pounds（100kg) per minute．3)Maximizing the Recovery of Metal Units. Clean，segregated scrap should be rapidly charged into the melting furnace, and the furnace should be completely closed. The melt should not be disturbed．However, if the dross formation is considered excessive, the furnace should be skimmed，and the skim immediately transferred to a closed chamber and covered with inert gas.When the melt reaches the correct temperature，it should be transferred (in a transfer system that eliminates turbulence) to the holding or casting furnace. Most remelt operations appear to ignore these simple rules．Operators are allowed to stir the melt. Metal is allowed to cascade from melting furnace to holding furnace, often creating mountains of dross where it enters the holder.4)Maximizing Energy (Fuel) Efficiency. Scrap aluminum, much of which will have been pre- heated when it was de-contaminated，together with pre-heated pig and some cold scrap，is rapidly charged into a hot furnace. As stated above, efficient scrap melting is done in a closed (sealed might be a better word) furnace. The combustion air, which must be pre-heated，must be rigorously controlled. Recuperation of heat from the furnace gases must not affect the combustion process.The holding furnace, and homogenizing furnaces, must likewise be designed and operated to maximize energy efficiency.5)Maximizing Product Mix:Alloy, Composition and Diameter. An efficient remelt and casting center will serve many customers，combining pig and available scrap，and recycling their scrap back to the customer's preferred composition(s), required log and billet dimensions．The product of the number of alloy compositions and the log diameters is the measure of product mix. Depending on the number of customers and their require, alloy-diameter variants can run into hundreds.To accommodate these variations, furnace campaigns must be planned to start melting and casting the pure aluminum alloys, then the common AAA6xxx alloys, followed by the hard alloys.6) Maximhefng Utiilzation of Equipment In an aluminum scrap remelt and casting center, the melting fumace(s）must inevitably be the production bottlenecks. All other equipment and operations must be designed, installed, and operated to ensure that the furnaces reach their full potential.This means that furnaces must be available at an rimes. Pumwe and utilization measured agakVt．standard of 24 X 7 X 52 i.e. 8736 annual hours. Maintenance time must therefore be minimized. This is accomplished by engineering all the equipment and operations (including the furnaces) to minimize the possibility of damage, and to maximize the life under normal operating conditions.Traditional aluminum scrap remelt and casting operations have been designed to accept a wide range of materials-smelter pig and ingot, customer scrap, reject log, billet and butts, extrusion scrap-often bundled or compressed-but also in mill lengths up to 21 feet (7m), and saw chips-loose and compressed into briquettes. This is usually loaded into rectangular furnaces through large doors, or if contaminated, into rectangular open wells. The loading (charging) operation is done using fork trucks or custom designed charging machines. The furnace doors, charging wells and roofs are inevitably damaged. The faster the charging operation, the greater is the resulting damage.7)Maximizing Labor bor productivity as measured in thousands of tons per person-year, is maximized when the plant throughput is maximized and the total number of people employed is at a minimum.8) Maintaining control of quality. Rigorous segregation of scrap, control of alloy additions and composition, together with the control of all processes-temperatures and times-including control of the dimensions of the product, ensure that the resulting homogenized log or billet meets quality The Ultimate Remelt and Casting Center.standards equivalent to prime smelter metal．Technology is available to deliver all the objectives listed above while meeting or exceeding all current and perceived future environmental regulations. All of the technologies are employed in aluminum scrap remelt and casting operations but, to the writer’s knowledge,to one installation combines all the technologies required to maximize the performance and financial returns. The technologies:1 Breaking bundles (bales), fabrications, and shearing long extrusions into short lengths, thereby maximizing the density of the extrusion scrap prior to charging into the melting furnace.2 Breaking bundles (bales), fabrications and shearing long extrusions into short lengths, thereby minimizing the possibility of damage to furnace walls and roof when the scrap is charged into the melting furnace.3 Continuously de-coating the short lengths of extrusion scrap, small pieces or fabricated aluminum, and saw chips to minimize the equipment required to eliminate effluents and meet all current environmental standards.4 Utilizing the energy released by the coatings, associated plastics：rubbers, and oils to preheat the scrap aluminum.5 Storing the heated aluminum to retain the energy.6 RaDidlv changing the heated aluminum scrap into the melting fumace.7 Employing circular top-charging melting fumace(s) equipped with a charging system that eliminates the possibility of damage to furnace floor, walls and roof.8 Employing circular top-charging melting furnace(s) with small sealed doors to ensure control of combustion．9 Using stack recuperators to pre-heat the combustion air.10 Employing circular top-charging melting fumace(s) constructed to extend the life between major repairs from months to years.Tilting the melting furnace(s) and thenoiaing turnace(s) to ensure that transfer ofmetal between the furnaces is turbulent-ree throughout the transfer of metal．Employing straight launder systems for all metal transfer and castinq，minimizing bothturoulence and the resulting wear. Engineering the holding furnace to enable complete access to the surface of the molten aluminum．Using stack recuperators to pre-heat the combustion air. Using in-line continuous addition of grain refiner rod．Using in-line degassing systems.Using in-line filtering systems．Using internally guided hydraulic casting machine to eliminate the potentially high maintenance external guide systems.Employing off-line set up station for the casting table.Using hot-top and Air-Slip casting technology.Using batch-homogenizing systems designed to ensure that the load is uniformly processed from end-to-end and side-to-side.Using continuous homogenizing systems designed to ensure that all logs are processed in the same manner.Using sawing systems that maximize the recovery of billet from each sawn log．CONCLUSIONBy selecting a number of available technologies and combining them into a state-of-the-art aluminum extrusion scrap remelt and casting center, the recycling industrty can produce billet wquialent to prime while minimizing its concersion cosrs and meeting all current encironmental saandsrds.REFERENCESArticles and papers relecant to the recycling of aluminum extrusion scrap prepared by the associates of BENCHMARKS and The Virtual Company Inc.,which have appeared since May 1996:1 ．Fielding, Roger A. P.，D. Hugh Barnard, and George. E. Macey, "The Role of Modeling in the Design and Operation of Remelt and Casting Facilities," Sixth International Extrusion Technology Seminar, V ol. I，Chicago, Illinois, May 1996, 437-442.2. Fielding，Roger A. P. and Carol F. Kavanaugh，"The Role of Grain Refining, Degassing，and Filtration in the Production of Quality Ingot Products," Light Metal Age, Vol．54，Nos. 9, 10 October 1996，46-59. (Contribution by Carol Kavanaugh on Effective and Efficient Measurement: The Design of Experiments.）3. Fielding, Roger A. P., "The Aluminum Association Standard Test Procedure for Aluminum Alloy Grain Refiners 1990: TP-1，A Case Study in Cooperative Development," Light Metal Age, Vol．55, Nos. 5,6, June 1997, 66-80.4. Fielding, Roger A. P.，"Recycling Secondary Aluminum Scrap at Roth Bros, Syracuse, N.Y.," Light Metal Age, Vol. 56, Nos．1，2, February 1998，99=101．5. Fielding, Roger A. P., "The Economy of Extrusion Scrap Recycling．The Metallurgical, Minerals and Metals Conference, TMS San Antonio TX, March 1998,”Light Metals, 1998,1137-1142.6 ．Bryant, A. J.，and Roger A. P. Fielding，"The Impact of Recent Developments in Billet and Extrusion Metallurgy on the Development of Equipment Technology," Light Metal Age, V ol. 56, Nos. 3,4, April 1998, 6-34．7. Bryant, A. J., and R. A. P. Fielding, "The Evaluation of Extrusion Billet from the Cast house 一Part I，，’Light Metal Age, V ol．57, Nos. 1,2, February 1999, 80-86.8. Bryant, A. J. and R. A. P. Fielding, "The Evaluation of Extrusion Billet from the Cast house 一Part II，，，Light Metal Age, V ol. 57, Nos. 3,4, April 1999, 78-82.9. Bryant, A. J.，W. Dixon, R. A. P. Fielding，and G. E. Macey, "Defects in Medium and High Strength Extrusion Alloys," Light Metal Age, V ol. 57，Nos. 5，6，June 1999，30-54.10. Bryant, A. J. and R. A. P. Fielding, "Recent Developments in Grain Refining，Degassing, and Filtration for the Production of Quality Ingot Products," Unpublished Report, August 2000. 11．Barnard，Hugh，"Evaluating Melting Furnace Combustion Systems," Light Metal Age, V ol.59, Nos.9, 10, October 2001，16, 17.12. Bryant, A. J., G. E. Macey, and R. A. P. Fielding, "Homogenization of Aluminum Alloy Extrusion Billet, Part I，，”Light Metal Age, Vol. 60, Nos. 3, 4, April 2002, 6-15.13. Bryant, A. J., G. E. Macey, and R. A. P. Fielding，"Homogenization of Aluminum Alloy Extrusion Billet, Part I．，＂Light Metal Age, V ol 60，Nos. 5，6，June 2002，18-27.中文译文：基本挤压冶炼和铸造的根源编写——罗杰托维奇菲尔丁——基准乔治英， Macey——Macey传热协会D 。

Mg-Zn-Al新型镁合金开发及半固态触变成形的开题报告一、研究背景及意义镁合金是轻质的金属材料，具有良好的可塑性、高比强度和良好的热导性能等优点，因此在航空航天、汽车工业、电子器件等领域得到了广泛的应用。

随着科技的进步和经济的发展，镁合金的需求量越来越大。

而在镁合金中，Mg-Zn-Al系列合金是一种新型的镁合金，具有高强度、较好的耐腐蚀性和较高的塑性等优点，因此受到了广泛的关注。

半固态触变成形是一种新兴的金属成形技术，能够在较低的温度下实现高精度、高质量、高效率的金属零件制造，具有很高的应用前景。

而Mg-Zn-Al系列合金在半固态触变成形中具有很大的潜力。

因此，开展Mg-Zn-Al新型镁合金的研究，探究其在半固态触变成形中的应用，具有十分重要的研究意义。

二、研究内容及技术路线本文的研究内容主要包括以下几个方面：1. Mg-Zn-Al新型镁合金的制备：选择合适的原料，采用熔铸、挤压等方法制备Mg-Zn-Al合金，并对合金进行组织结构和成分分析。

2. Mg-Zn-Al新型镁合金的力学性能测试：通过拉伸、压缩等试验，测试Mg-Zn-Al新型镁合金的力学性能，包括屈服强度、延伸率、断裂强度等参数。

3. 半固态触变成形工艺研究：首先确定半固态触变成形的工艺参数，包括温度、应变速率等；然后利用实验验证Mg-Zn-Al新型镁合金在半固态触变成形中的可行性，并分析影响成形质量及产品性能的因素。

4. 复合成形技术研究：将半固态触变成形技术与其他成形技术结合，如注射成形技术、挤压成形技术等，形成多种复合成形技术，并对其进行比较分析。

技术路线如下：三、预期研究成果1. 成功制备出Mg-Zn-Al新型镁合金，并对其组织结构和成分进行了分析。

2. 测试出Mg-Zn-Al新型镁合金在拉伸、压缩等试验中的力学性能。

3. 确定了Mg-Zn-Al新型镁合金在半固态触变成形中的工艺参数，并对其成形性能进行了分析。

4. 研究出了Mg-Zn-Al新型镁合金的多种复合成形技术，并进行了比较分析。

Semisolid extrusion moldingof Mg-9%Al-1%Zn alloysF. CZERWINSKIDevelopment Engineering, Husky Injection Molding Systems Ltd., Bolton,Ontario, L7E 5S5, CanadaA novel technique in manufacturing net-shape components of magnesium alloys, which combines semisolid processing, extrusion and injection molding, is outlined. For an Mg-9%Al-1%Zn composition, the high-temperature transformations and factors controlling solidification microstructures, are analyzed. C _ 2004 Kluwer Academic Publishers1. IntroductionExtrusion is the plastic deformation process by which a metal is forced to flow by compression through the die orifice of a smaller cross-sectional area than that of the original billet. Since the material is subjected to compressive forces only, the extrusion is an excellent method for breaking down the cast structure of the billet with little or no cracking [1]. Most metals are extruded hot when the billet is preheated to facilitate plastic deformation, but room temperature (cold) extrusion is also exercised. So far, conventional extrusion applications do not utilize preheating materials above the solidus temperature to enter the semisolid range.The advantages of processing metallic alloys in a semisolid state are attributed to the globular solid particles which control their thixotropic properties at high temperatures and reduce the content of dendritic forms after subsequent solidification [2]. It is well established that the benefits associated with semisolid processing, such as low shrinkage porosity, high tolerances and energy savings, are more evident at high solid fractions. Moreover, the ability to cast at higher solid fractions is of interest in improving billet stability and minimizing material loss during handling.Of all semisolid technologies, injection molding provides the largest flexibility in terms of the processed solid contents [3]. This feature is attributed to the fact that injection molding combines the slurry making and component forming operations into one step, and the slurry is accumulated in a direct vicinity of the mold gate. So far, these potentials are not explored and commercial applications are limited to liquid-rich slurries, which, for thin-wall sections, may contain solid volumes as low as 5–10%. As the major obstacle preventing using high solid contents, the premature alloy’s freezing and incomplete filling the mold cavity, is reported [4]. It was,therefore, anticipated that a drastic increase in solid content, especially above 60%, would transform the flow through the machine nozzle, runners, and mold gate into the extrusion, thus activating interaction between solid particles within the slurry which would facilitate the mold filling. The verification of such a hypothesis was the objective of this study.2. Experimental detailsAZ91D magnesium alloy, used in the present study, had a nominal composition of 8.5% Al, 0.75% Zn, 0.3% Mn, 0.01% Si, 0.01% Cu, 0.001% Ni, 0.001% Fe and an Mg-balance. An as-cast ingot was mechanically converted into small chips and processed using a Husky TXM500-M70 prototype system with a clamp force of 500 tons and a 2 m long barrel with a diameter of 70 mm. The component manufactured represented the complex shape with a diameter of 190 mm and a total weight, including sprue and runners, of 582 g [3]. The mold was preheated to 200◦C and the slurry was injected at a screw velocity in the range of 0.7–2.8 m/s. For the gate opening of 221.5 mm2 it converts to the alloy’s velocity at the mold’s gate between 12.2 and 48.6 m/s. In order to examine the role of flow through the gate, the alloy was also injected (purged) into the partly open mold at significantly lower flow velocity at the mold gate. The typical cycle time was approximately 25 s, which corresponds to an average residency time of the alloy within the machine barrel of the order of 100 s. In some cases, the cycle time was deliberately extended up to 4 times. Metallographic samples of the molded alloy were prepared by grinding with progressively finer SiC paper, mechanical polishing with 1 μm diamond paste and colloidal alumina, followed by etching in a 1% solution of nitric acid in ethanol. Stereological analysis was conducted using optical microscopy, equipped with a quantitative image analyzer.3. Results3.1. Structural transformations of the alloy during processingMorphologies of an as-chipped alloy are shown in Fig. 1a. According to size determination by the screen method ASTM E-276-68, the predominant fraction of chips was retained on sieves with openings within the range 0.6–2 mm, and 75% of them did not pass through the 1.4 mm sieve. As a result of interaction with the chipping tool, the alloy experienced a cold work. The chips’ deformation is inhomogeneous with an increased strain in an immediate location of the second phase particles (Fig. 1b).(a)(b)(c)Figure 1The initial state and thermal decomposition of Mg-9%Al-1%Zn feedstock, used during experiments: (a) as-received chips, (b) chip’s crosssection with cold-work features and (c) early stage of chip’s melting, showing disintegration of equiaxed network of recrystallized grains; the chemical segregation contour of former dendritic features, consumed by equiaxed grains is marked as “s”.Figure 2 The schematic diagrams of structural transformations of a magnesium alloy during various stages of the semisolid extrusion molding.As proven by chips melting outside the molding system, dendritic structure disintegrated completely by the solid-state reaction (Fig. 1c). During heating inside the machine barrel, the structure recrystallized by nucleation and the growth of equiaxed grains. The second phase, intermetallic compound Mg17Al12, was distributed mainly along grain boundaries. In addition, grain boundaries were enriched in the solute element Al. After exceeding the solidus temperature, the melting started at grain boundaries leading first to the generation of equiaxed, thenglobular solid particles, surrounded by the liquid metal (Fig. 1c). The summary of major structural transformations during semisolid extrusion molding is shown in Fig.2. Thus, during further conveying of the slurry along the barrel, the globular structures of the unmelted phase experienced breakdown and agglomeration due to the combined effect of external heat and strain. As a result of diffusion, the solid phase was also subjected to coalescence and Ostwald ripening, as discussed in detail previously [5]. After melting of the grain boundary network, the semisolid slurry, with globular solid particles, was essentially ready for the component-forming step,i.e. the injection into a mold cavity.3.2. Solidification microstructuresThe microstructure, typical for ultra-high solids is comprised predominantly of unmelted particles of α-Mg, surrounded by a solidification product of the former liquid phase. As seen in Fig. 3a, the particle’s shape is near globular, but with increasing solid fraction it shows a tendency to be more constrained geometrically, exhibiting shape accommodation. The former liquid cover the grain boundary network with small pools accumulated at triple junctions. There were also randomly distributed larger islands of the liquid; however, they were generally smaller than the solid particle. The portion of the former liquid which was entrapped within solid particles showed high dispersion. Thus, instead of single island morphologies, frequent for medium and lower solid fractions [6], there were numerous randomly distributed precipitates of smaller size and globular shape. It is likely that some of them were formed by solid-state precipitation from the supersaturated solid solution than by solidification of the Al-rich liquid.3.3. Microstructural feedback towards the high-temperature stageThe detailed examination of room-temperature microstructures provided important information regarding phenomena which take place at high temperatures. A strong influence of alloy injection velocity on the solidification morphologies was discovered. An example in Fig. 3b represents the structure formed from the slurry with the same initial solid content as that in Fig. 3a. The major processing difference was approximately a 100% increase in the mold gate opening and component wall thickness. The structure in Fig. 3b solidified in 4 mm-thick sections. Thus, reduction in injection velocity, combined with increased component wall thickness, led to the transition from globular particles surrounded by freshly solidified matrix to equiaxed grains. Some occasional islands of the former liquid were distributed at triple junctions. There is no substantial difference in the volume fraction and dispersion degree of precipitates within grain interiors, as compared to those present withinglobular solid particles (Fig. 3a).The quantitative description of the influence of the injection rate on the molded structure is shown in Fig. 4. The first finding is that for a given initial solid content within the slurry, the higher injection velocity led to an increased liquid content inside the part. In addition, the injection velocity affected the homogeneity of solid particle distribution, particularly across the part thickness. While for the gate velocity of 12.2 m/s the solid fraction across the part thickness of 2 mm remained constant, the velocity of 48.6 m/s caused an increase in the liquid fraction towards the component outer surface. For 12.2–48.6 m/s range of injection velocities, there was an increase in average liquid content from 15 to 25%. It seems that there was not close relationship between the solid content or its distribution and a size of the unmelted phase, which is characterized by the histogram in the insert of Fig. 4. The solid particle size was, however, strongly affected by the alloy’s residency time inside the machine barrel. An increase of average cycle time by four times, resulting in a total residency time of 400 s increased the average particle size from 33 μm to 60 μm.4. Discussion of resultsThe key requirement of semisolid processing is the thixotropic slurry with(a)(b)Figure 3The microstructure of AZ91D alloy obtained from the slurry with the same solid fraction: (a) globular structure, injection velocity of 48.6 m/s, wall thickness of 2 mm and (b) equiaxed structure, injection velocity of 5 m/s, wall thickness of 4 mm.non-dendritic morphologies of the unmelted phase. Our finding [6, 7] that the cold work, imposed on chips during their manufacturing, is a driving force for the generation of globular forms by the mechanism of recrystallization and grain boundary disintegration implies that such a slurry is formed at the very beginning of melting (Fig. 1b and c). Since all benefits are associated with the unmelted solid phase it would appear that the liquid content should be kept as low as possible. However, a certain liquid content is required to ensure processibility, defined as the macroscopically homogeneous and damage free flow. This minimum depends on the alloy type, and for the aluminum alloy A 2014, deformed in an unconstrained compression, it was as low as 20% [8]. In the case of this study, the minimum value was even lower (Fig. 4).It is generally accepted that, at ultra-high solid contents, the alloy represents a deformable, semi-cohesive granular solid, saturated with liquid. When subjected to external strain, the alloy will respond by the disagglomeration of partially bonded grains. It is highly possible that, due to the shear imposed by the screw and relatively short rest time, there is no bond between the solid particles accumulated directlybefore injection. Analyses of as-solidified structures (Figs 3a and 4) and machine operating parameters suggest that phenomena of solid/solid interaction within the slurry with ultra high solid contents are significantly more intense than those described for low and medium solid contents. During semisolid injection molding, the mold filling time is the key factor which controls the entire process [3]. If the material experiences solidification (freezing), it reduces the cross section of the flow channel and increases the effective filling time. It is suspected that the interparticle interference, at the stage of injection, facilitates the mold filling process. This hypothesis is supported not only by the complete mold filling, but also by the fact that the mold filling time was approximately 0.025 s, which is of the same order of magnitude as that measured for low solid contents.Figure 4The inhomogeneity in the distribution of solid particles within the component, extrusion molded in a semisolid state. The inset shows a typical histogram of solid-size distribution at middle-wall thickness.The characteristic feature of microstructures produced by semisolid extrusion molding is the small size of the unmelted phase (Fig. 4, inset). This size being of 34μm, is very similar to the grain size within the recrystallized chip and was believed to be preserved by external shear causing disagglomeration [5, 9]. An increase in the cycle time to 100 s mainly affected the alloy’s residency time in an absence of shear. It is natural that the system reduces its energy by particle growth, althoughmechanisms may differ from those described for low solid contents. At solid fractions above 0.5, coarsening behaviour can better be described by considering the migration of the liquid films separating the grains, than by considering diffusion fields around isolated solid grains, as in the Lifshitz, Slyozov and Wagner analysis [10]. Coarsening cannot be used exclusively to explain the formation of the equiaxed structure in Fig. 3b. Rather, the reduced gate velocity and longer solidification time, caused by thicker alloy section, provide a better answer. According to this mechanism, solidification of the liquid portion of the alloy takes place on pre-existing globular substrates as described earlier for large slurry volumes, which solidified inside the machine barrel [9].The inhomogeneities in the solid phase distribution of as-solidified structures (Fig. 4) result from the flow characteristics during mold filling. The higher solid content in the part than within the runner should be interpreted as resulting from melting during slurry flow through the narrowgate channels. Similar findings were reported for experiments of the back extrusion of Sn-Pb alloy with an effective liquid fraction of less than 0.30, where it was found that the liquid fraction was a function of the extrusion ratio increasing as the wall thickness decreased [11]. Another possibility of the selective flow where the liquid fraction is pushed through the solid skeleton seems to be diminished, from the microstructural analysis of samples taken along the alloy flow path. The relatively high flow velocity of the alloy during mold filling and specific gravity difference between solid and liquid causes phase segregation. For an injection velocity of 49.6 m/s, the liquid content close to the outer surface is about 20% higher than in the center (Fig. 4). Details of the inhomogeneous distribution of the solid phase within the part still requires explanation.5. ConclusionsThe elements of semisolid processing, extrusion and injection molding were successfully combined to manufacture net shape components of Mg-9%Al-1%Zn alloy starting from a slurry with high solid contents of the order of 70%. The resultant solidification microstructures ranged from globular forms surrounded by the former liquid matrix to exclusively equiaxed grains.At high temperatures, the unmelted particles were susceptible to coarsening with increased residency time and the homogeneity in their distribution within the part was influenced by the injection velocity. It is believed that the phenomenon of solid particle interference during slurry flowunder compressive forces facilitated filling the mold cavity.References1. G. E. DIETER, “Mechanical Metallurgy” (McGraw-Hill, New York, 1976).2. M. C. FLEMINGS, Metall. Trans. A 22 (1991) 957.3. F . CZERWINSKI, Adv. Mater. Proc. 160/11 (2002) 31.4. D. M. WALUKAS, R. E. VINING, S . E. LEBEAU, N. TANIGICHI and R. F . DECKER, Advanced Semisolid Processing of Alloys and Composites, edited by Y. Tsutsui, M. Kiuchi andK. Ichikawa, Tsukuba, Japan, 2002, p. 101.5. F . CZERWINSKI, Scripta Mater. 48 (2003) 327.6. F . CZERWINSKI, A. ZIELINSKA-LIPIEC, P . J . PINET and J . OVERBEEKE, Acta Mater. 49 (2001) 1225.7. F . CZERWINSKI, ibid. 50 (2002) 3265.8. E. TZIMAS and A. ZAVALIANGOS, ibid. 47 (1999) 517.9. F . CZERWINSKI, Metall. Mater. Trans. A 33 (2002) 2963.10. E. D. MANSON-WHITTON, I . C. STONE, J . R. JONES,P . S . GRANT and B. CANTOR, Acta Mater. 50 (2002) 2517.11. T. BASNER, R. PEHLKE and A. SACHDEV, Metall. Mater. Trans. A 31 (2000) 57.Received 23 Apriland accepted 12 August 2003材料科学期刊39 (2004)463-468Mg-9Al-1Zn合金的半固体挤压成型凯泽韦斯基开发工程师,赫斯基注塑系统有限公司,博尔顿,安大略,L7E 5 S5,加拿大这种结合半固体加工、挤出和注塑综合作用的新技术，应用在生产制造网状的镁合金部件。