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附着强度英语Adhesive StrengthThe concept of adhesive strength is a fundamental aspect of material science and engineering, with far-reaching implications in various industries. Adhesives are materials that facilitate the bonding of two or more surfaces, creating a strong and durable connection. The strength of this bond, known as adhesive strength, is a critical factor in determining the overall performance and reliability of the joined components.Adhesive strength is influenced by a multitude of factors, including the chemical composition of the adhesive, the surface properties of the materials being bonded, the environmental conditions, and the applied stresses. Understanding and optimizing these factors is crucial for ensuring the integrity and longevity of adhesive-based assemblies.One of the primary determinants of adhesive strength is the chemical composition of the adhesive itself. Adhesives can be classified into various categories, such as epoxies, acrylics, silicones, and polyurethanes, each with its own unique properties andperformance characteristics. The choice of adhesive depends on the specific application, the materials being bonded, and the desired level of strength and durability.Epoxy adhesives, for instance, are known for their exceptional strength and resistance to environmental factors, making them a popular choice for applications in the aerospace, automotive, and construction industries. These adhesives form a strong covalent bond with the substrate, resulting in a high-strength connection that can withstand significant stresses and loads.Acrylic adhesives, on the other hand, offer a more versatile and flexible bonding solution. They are commonly used in the electronics and consumer goods industries, where the ability to bond a wide range of materials, including plastics and metals, is essential. Acrylic adhesives typically exhibit good impact resistance and can accommodate slight movements or deformations in the bonded components.Silicone adhesives, in contrast, are prized for their excellent resistance to high temperatures, weathering, and chemical exposure. They are often employed in applications where these environmental factors are a concern, such as in the automotive, aerospace, and construction industries. Silicone adhesives can form strong bonds with a variety of substrates, including glass, metal, and plastic.Polyurethane adhesives, meanwhile, are known for their superior flexibility and impact resistance. They are commonly used in the construction and transportation industries, where the ability to accommodate movement and vibration is crucial. Polyurethane adhesives can form strong bonds with a wide range of materials, including wood, concrete, and various plastics.The surface properties of the materials being bonded also play a significant role in determining the adhesive strength. The surface roughness, wettability, and chemical composition of the substrates can influence the adhesive's ability to form a strong and durable bond. Surface preparation techniques, such as cleaning, etching, or priming, can be employed to enhance the adhesion properties of the materials, thereby improving the overall adhesive strength.Environmental factors, such as temperature, humidity, and exposure to chemicals or UV radiation, can also have a significant impact on the adhesive strength. Adhesives may experience degradation or weakening over time due to these environmental stresses, leading to a reduction in the overall bond strength. Understanding and mitigating these environmental factors is essential for ensuring the long-term performance and reliability of adhesive-based assemblies.The applied stresses on the bonded assembly are another criticalfactor in determining the adhesive strength. Adhesives can experience various types of stresses, including tensile, shear, peel, and cleavage stresses, each of which can have a different effect on the bond strength. Designing the bonded assembly to minimize the impact of these stresses, through the use of appropriate joint geometries and load-bearing configurations, can help maximize the adhesive strength and ensure the overall integrity of the assembly.In addition to these fundamental factors, advances in adhesive technology have led to the development of specialized adhesives that can further enhance the adhesive strength. For example, structural adhesives, which are designed to withstand high loads and stresses, are commonly used in the aerospace and automotive industries. These adhesives can provide superior strength and durability, often outperforming traditional mechanical fasteners in certain applications.Another example of advanced adhesive technology is the use of nanoparticle-reinforced adhesives. These adhesives incorporate nanoscale reinforcements, such as carbon nanotubes or graphene, which can significantly improve the adhesive strength, toughness, and thermal stability of the bond. The incorporation of these nanomaterials can lead to enhanced interfacial interactions between the adhesive and the substrate, resulting in a stronger and more resilient bond.In conclusion, adhesive strength is a critical factor in the design and performance of a wide range of products and structures. Understanding the factors that influence adhesive strength, such as the chemical composition of the adhesive, the surface properties of the materials being bonded, environmental conditions, and applied stresses, is essential for ensuring the reliability and durability of adhesive-based assemblies. Advances in adhesive technology, including the development of specialized structural adhesives and nanoparticle-reinforced adhesives, have further expanded the capabilities and applications of adhesive bonding in various industries.。
刘容旭，李春雨，王语聪，等. 超高压辅助酶解法改性汉麻分离蛋白及其理化性质的研究[J]. 食品工业科技，2023，44（19）：99−107.doi: 10.13386/j.issn1002-0306.2023010016LIU Rongxu, LI Chunyu, WANG Yucong, et al. Study on the Modification and Physicochemical Properties of Hemp Protein Isolate by Ultra-High Pressure Assisted Enzymatic Hydrolysis[J]. Science and Technology of Food Industry, 2023, 44(19): 99−107. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023010016· 研究与探讨 ·超高压辅助酶解法改性汉麻分离蛋白及其理化性质的研究刘容旭1，李春雨2，王语聪2，谢智鑫2，谢宜桐2，李双鹏2，刘丹怡1, *，韩建春2,*（1.黑龙江省绿色食品科学研究院，黑龙江哈尔滨 150028；2.东北农业大学 食品学院，黑龙江哈尔滨 150030）摘 要：本研究以汉麻分离蛋白（Hemp Protein Isolate ，HPI ）为原料，通过超高压辅助酶解反应对HPI 进行改性，以溶解度和水解度为判定指标筛选酶解改性反应最佳条件，并探究超高压辅助酶解反应对酶解产物溶解性、起泡性、乳化性、持水性、持油性的影响。
结果表明，HPI 酶解反应最适条件为：加酶量（复合蛋白酶）5000 U/g 、酶解改性pH8.0、酶解改性温度55 ℃、酶解改性时间50 min 。
以HPI 为对照，当压力为200 MPa 时，酶解产物的溶解度、起泡性、乳化性、持油性最高，压力为100 MPa 时，泡沫稳定性最好，酶解后的乳化稳定性存在不同程度的下降，压力为0.1 MPa 时其持水性达到最大值。
如何解决疲劳效应英语作文Title: Strategies to Combat Fatigue Effect。
Fatigue effect, the depletion of mental and physical energy over time, poses a significant challenge to individuals in various aspects of life, be it academic, professional, or personal. Addressing this issue requires a multifaceted approach encompassing lifestyle adjustments, cognitive strategies, and self-care practices. In this essay, we will delve into effective methods to tackle fatigue effect and enhance overall well-being.Firstly, establishing a balanced lifestyle is paramount in combating fatigue. Adequate sleep is fundamental for replenishing energy levels and sustaining cognitive function. Research suggests that adults should aim for 7-9 hours of sleep per night for optimal health. Additionally, maintaining a consistent sleep schedule, even on weekends, helps regulate the body's internal clock, promoting better sleep quality and reducing daytime fatigue.Moreover, incorporating regular physical activity into one's routine is beneficial for combating fatigue. Exercise stimulates the release of endorphins, neurotransmittersthat elevate mood and energy levels. Engaging in activities such as jogging, yoga, or swimming not only enhances physical fitness but also boosts mental clarity and alertness. Even short bouts of exercise throughout the day can mitigate feelings of fatigue and improve overall productivity.In conjunction with lifestyle modifications, adopting cognitive strategies can mitigate the impact of fatigue on cognitive function. Time management techniques, such as the Pomodoro Technique, involve breaking tasks into manageable intervals separated by short breaks. This method prevents burnout and enhances focus by capitalizing on the brain's natural rhythm of attention.Furthermore, implementing mindfulness practices can counteract the cognitive effects of fatigue. Mindfulness meditation, characterized by non-judgmental awareness ofthe present moment, promotes mental clarity and resilience to stress. Studies have shown that regular meditation reduces fatigue and enhances cognitive flexibility, enabling individuals to navigate challenges with greater ease.In addition to lifestyle and cognitive interventions, self-care practices play a crucial role in combatingfatigue effect. Nutrition plays a pivotal role in sustaining energy levels throughout the day. Consuming a balanced diet rich in whole grains, lean proteins, fruits, and vegetables provides essential nutrients that support optimal brain function and mitigate fatigue.Moreover, practicing self-compassion and setting realistic expectations are vital components of self-care. Perfectionism and excessive self-criticism can contribute to burnout and exacerbate feelings of fatigue. Cultivating self-compassion involves treating oneself with kindness and understanding, particularly during periods of heightened stress or fatigue.Furthermore, establishing boundaries and prioritizing self-care activities is essential for preventing burnout. Carving out time for leisure activities, social connections, and relaxation fosters resilience and replenishes depleted energy stores. Whether it's reading a book, spending time with loved ones, or engaging in hobbies, prioritizing activities that bring joy and fulfillment is essential for maintaining well-being.In conclusion, addressing fatigue effect necessitates a comprehensive approach encompassing lifestyle adjustments, cognitive strategies, and self-care practices. Byprioritizing sleep, exercise, mindfulness, nutrition, and self-compassion, individuals can mitigate the impact of fatigue and cultivate resilience in the face of challenges. Empowering oneself with effective coping mechanisms is keyto sustaining energy levels and optimizing overall well-being.。
第44卷第6期2021年6月V ol.44，No.6June2021核技术NUCLEAR TECHNIQUES熔盐堆低功率工况下反应性引入事故初始条件敏感性探讨焦小伟王凯王超群杨群何兆忠（中国科学院上海应用物理研究所上海201800）摘要熔盐堆低功率工况反应性引入事故中，不同的反应性引入速率将触发不同的停堆信号。
同时反应堆初始功率和反应性温度系数等初始条件影响事故的进程，引起事故后果的差异。
本文选取了7个反应性引入速率工况、25个初始功率水平和反应性温度系数的参数组合初始工况，分别讨论了这三个参数对事故后果的影响。
分析结果表明：熔盐堆低功率工况反应性引入事故的后果对反应性引入速率的变化较敏感，在其他初始条件一定的情况下，存在特定的反应性引入速率会导致最不利的事故后果；事故后果对反应堆初始功率和反应性温度系数的变化不敏感，由初始功率和反应性温度系数差异造成的事故后果差异较小。
关键词熔盐堆，低功率，反应性引入事故，敏感性中图分类号TL36DOI:10.11889/j.0253-3219.2021.hjs.44.060602Study on sensitivity of initial conditions of reactivity initiated accident under low powerconditions of molten salt reactorJIAO Xiaowei WANG Kai WANG Chaoqun YANG Qun HE Zhaozhong(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai201800,China)Abstract[Background]In the reactivity initiated accidents under low power operating conditions of molten salt reactor(MSR),different reactivity insertion rates will trigger different emergency shutdown signals.At the same time,the initial conditions such as the initial reactor power and the temperature coefficients of reactivity affect the accident process and cause differences in accident consequences.[Purpose]The study aims to conduct a sensitivity analysis of the impact of the reactivity insertion rate,the initial reactor power,and the reactivity temperature coefficient on transient consequences.[Methods]First of all,7reactivity insertion rate conditions were selected and simulated through RELAP5-TMSR.Then,25combinations of the initial reactor power and the temperature coefficients of reactivity were assumed as initial conditions.Finally,the effects of these three parameters on the consequences of the accident were discussed separately by using local sensitivity analysis method.[Results]The insertion rate that causes a concurrent trigger of the high outlet temperature and the high-power shutdown signal leads to the most unfavorable consequence.The difference between the peak temperatures of the fuel salt and structural materials and their respective initial values under the worst reactivity insertion rate condition is negatively correlated with initial power.However,the temperature difference of each parameter caused by different initial power does not中国科学院青年创新促进会项目(No.Y929022031)资助第一作者：焦小伟，男，1989年出生，2019年于中国科学院大学获博士学位，副研究员，主要从事反应堆事故分析通信作者：杨群，E-mail：收稿日期：2021-01-14，修回日期：2021-03-29Supported by the Project of Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y929022031)First author:JIAO Xiaowei,male,born in1989,graduated from University of Chinese Academy of Sciences with a doctoral degree in2019,associate professor,focusing on reactor safetyCorresponding author:YANG Qun,E-mail:Received date:2021-01-14,revised date:2021-03-29焦小伟等：熔盐堆低功率工况下反应性引入事故初始条件敏感性探讨exceed3℃.The difference between the peak temperatures decrease first and then increases with the increase of the temperature coefficients of reactivity,but the maximum difference does not exceed0.5℃.[Conclusions]Under low power operating conditions of MSR,the consequences of reactivity introduced events are highly sensitive to the reactivity insertion rate and low sensitivity to the initial power and temperature coefficients of reactivity.Key words Molten salt reactor,Low power,Reactive initiated accident,Sensitivity熔盐堆（Molten Salt Reactor，MSR）是第四代核能系统候选堆型之一。
The Effect of Temperature on ProteinConformationProteins are essential components of living organisms and are responsible for carrying out various cellular functions. They are composed of long chains of amino acids that are folded into intricate 3-dimensional structures. The specific shape of a protein, or its conformation, plays a critical role in its function. Temperature is one of the key factors that can influence protein conformation. In this article, we will explore the effect of temperature on protein conformation and how it impacts their function.Temperature-induced protein denaturationProtein denaturation is a process in which the protein loses its native conformation and unfolds into a linear or random coil structure. This process can be triggered by several factors, including pH, salts, mechanical stress, and temperature. Among these, temperature is the most commonly studied factor that can induce protein denaturation.When proteins are exposed to high temperatures, the thermal energy causes the bonds that hold the protein structure together to break. Hydrogen bonds, which are weaker than covalent bonds, are the first to be broken. As the temperature continues to rise, the more significant covalent bonds that hold the protein together begin to break, further destabilizing the structure. Ultimately, the protein loses its native conformation, and its function is impaired.The effect of temperature on protein stabilityThe stability of a protein refers to its ability to maintain its native conformation in the face of various environmental conditions, including temperature. The stability of a protein is influenced by several factors, including the amino acid sequence, solvent conditions, and the presence of ligands or cofactors. Temperature can disrupt the stability of a protein by altering its structure and causing it to denature.Proteins have a range of thermal stability that depends on their amino acid sequence and their specific structure. Generally, proteins that are stable at higher temperatures have a higher content of hydrophobic amino acids, which can help to stabilize the structure through hydrophobic interactions. In contrast, proteins that are stable at lower temperatures tend to have more polar amino acids and a lower content of hydrophobic amino acids.The temperature at which a protein denatures is known as its melting temperature or Tm. The Tm of a protein is influenced by its intrinsic stability as well as the specific conditions under which it is studied. For example, the pH, salt concentration, and presence of other molecules can all affect the Tm of a protein.The effect of temperature on protein functionThe specific conformation of a protein plays a critical role in its function. Therefore, changes in protein conformation due to temperature can have a significant impact on their function. The effect of temperature on protein function can vary depending on the specific protein and the conditions under which it is studied.Some proteins are more sensitive to changes in temperature than others. For example, enzymes, which catalyze chemical reactions in the cell, have a specific optimal temperature range at which they function best. Outside of this range, the reaction rate can slow down or even stop altogether due to changes in protein conformation.Other proteins, such as transporters and receptors, are also sensitive to changes in temperature. Changes in protein conformation due to temperature can affect the ability of these proteins to bind to their ligands and carry out their function.ConclusionIn conclusion, temperature has a significant impact on protein conformation. High temperatures can cause proteins to denature, while changes in temperature can alter their stability and affect their function. Understanding the effect of temperature on protein conformation and function is essential for designing experiments and developing new drugs and therapies that target specific proteins.。
压力交变试验英语Stress Alternating TestStress is an integral part of our daily lives, and it can have a significant impact on our physical and mental well-being. The ability to manage stress effectively is crucial for maintaining a healthy and balanced lifestyle. One method of assessing and understanding the effects of stress is through the use of a stress alternating test.The stress alternating test is a technique used to evaluate an individual's response to varying levels of stress. The test involves exposing the subject to a series of controlled stress-inducing situations, alternating between high and low-stress conditions. This approach allows researchers and clinicians to observe how the body and mind react to the fluctuations in stress levels.During the stress alternating test, the subject may be asked to perform a variety of tasks or engage in different scenarios that are designed to elicit specific stress responses. For example, the subject may be required to solve complex mathematical problems under time pressure, engage in public speaking, or participate in simulated high-stakes decision-making scenarios. The test may also involveexposing the subject to environmental stressors, such as loud noises, extreme temperatures, or challenging physical activities.As the subject navigates through these varying stress conditions, researchers closely monitor a range of physiological and psychological parameters. These may include heart rate, blood pressure, cortisol levels, skin conductance, and self-reported measures of anxiety, mood, and cognitive performance. By analyzing these data points, researchers can gain insights into how the individual's body and mind respond to the fluctuations in stress levels.One of the key benefits of the stress alternating test is its ability to provide a comprehensive understanding of an individual's stress resilience. By observing how the subject's physiological and psychological responses change in response to the alternating stress levels, researchers can identify patterns and identify potential areas of vulnerability or strength. This information can then be used to develop personalized stress management strategies and interventions.Moreover, the stress alternating test can also be valuable in the context of occupational health and safety. Many professions, such as emergency services, military, and high-stakes decision-making roles, often require individuals to navigate high-stress situations regularly.The stress alternating test can be used to assess the suitability and resilience of individuals for these demanding roles, ensuring that they are equipped to handle the challenges they may face.In addition to its practical applications, the stress alternating test also contributes to our scientific understanding of the human stress response. By studying the physiological and psychological reactions to varying stress levels, researchers can gain insights into the underlying mechanisms that govern the stress response. This knowledge can then be used to develop more effective strategies for stress management and prevention, ultimately improving overall health and well-being.In conclusion, the stress alternating test is a valuable tool for assessing and understanding the effects of stress on the human body and mind. By exposing individuals to controlled stress-inducing situations and monitoring their responses, researchers and clinicians can gain valuable insights that can be used to develop personalized stress management strategies and interventions. As we continue to navigate the challenges of modern life, the stress alternating test will likely play an increasingly important role in promoting health, well-being, and resilience.。
Unit 3 Science and nature Section Ⅲ Word power，Task & ProjectⅠ品句填词1．Use your good ____________(判定) before you decide.答案：judgement2．The ____________ (多数) of students find it hard to accept the new theory.答案：majority3．From his ____________(可怕的) look，I guess he must have found something horrible.答案：frightened4．No one is to leave the building without my ____________(许诺)．答案：permission5．Please reenter your password to____________(确认) it is correct.答案：confirmⅡ单句改错1．I’d say she is pretty rich，judge from her →judging2．The project，conducting by our headmaster，has won the students’→conducted3．There was frost on the ground，confirmed that fall had arrived in →confirming4．This frighten boy whose mother was lost in the disaster is looking for her →frightened 5．We view the holi day for a time for recreation，but she has a different idea.第一个for→as Ⅲ完成句子1．就我个人而言，这部电影糟糕透顶。
鲶鱼效应可以有效促进竞争英语作文The Catfish Effect stimulates competition in various fields, propelling individuals to achieve greater accomplishments. This phenomenon describes the notion that if a small entity enters a larger competitive environment, it can motivate the established players to work harder and achieve better results. This effect can be observed in different domains such as sports, education, technology, and business.In sports, the Catfish Effect is often witnessed when a talented newcomer emerges and challenges the established athletes. The presence of this new talent motivates the existing players to train harder, improve their skills, and maintain their position at the top. The competition created by the Catfish Effect drives athletes to push beyond their limits, breaking records and achieving remarkable feats.Similarly, in the field of education, the Catfish Effect can enhance competition among students. When a new student with exceptional abilities joins a class, it inspires others to strive for excellence. The existing students realize the need to work harder, study more rigorously, and actively participate in academic activities to maintain their academic standing. This competitive environment fosters a culture of continuous improvement and enhances overall academic performances.The Catfish Effect is also evident in the realm of technology. When a small startup with an innovative idea enters an industry dominated by established companies, it often disrupts the market. The established companies recognize the potential of the new entrant and are motivated to innovate and develop better products or services in order to maintain their market share. This healthy competition drives technological advancements, benefiting consumers with improved offerings.Moreover, in the world of business, the Catfish Effect fuels healthy competition among companies. When a new player emerges with a unique value proposition or a disruptive business model, it compels existing companies to reassess their strategies and find ways to stay competitive. Established companies may invest in research and development, improve their products or services, or enhance customer experiences to successfully counter the competition andretain their market position.In conclusion, the Catfish Effect is a catalyst for competition in various domains. It motivates individuals and entities to step up their game, work harder, and strive for excellence. This effect has a positive impact on sports, education, technology, and business, fostering innovation and enhancing overall performances. The presence of new players creates an environment of healthy competition, pushing everyone to reach their full potential.。
Accepted ManuscriptEffect of Sn addition on stress hysteresis and superelastic properties of aTi-15Nb-3Mo alloyMuhammad Farzik Ijaz, Hee Young Kim, Hideki Hosoda, Shuichi MiyazakiPII:S1359-6462(13)00505-8DOI:/10.1016/j.scriptamat.2013.10.007Reference:SMM 10081To appear in:Scripta MaterialiaReceived Date:12 September 2013Revised Date:8 October 2013Accepted Date:10 October 2013Please cite this article as: M.F. Ijaz, H.Y. Kim, H. Hosoda, S. Miyazaki, Effect of Sn addition on stress hysteresis and superelastic properties of a Ti-15Nb-3Mo alloy, Scripta Materialia(2013), doi: /10.1016/ j.scriptamat.2013.10.007This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Effect of Sn addition on stress hysteresis and superelasticproperties of a Ti-15Nb-3Mo alloyMuhammad Farzik Ijaz a , Hee Young Kim a,*, Hideki Hosoda b and Shuichi Miyazaki a,c,** a Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573,Japan b Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama226-8503, Japanc Center of Excellence for Advanced Materials Research, King Abdulaziz University,PO Box 80203, Jeddah 21589, Saudi Arabia* Corresponding author. Tel./Fax: +81 29 853 6942.**Corresponding author. Tel./Fax: +81 29 853 5283. E-mail addresses: heeykim@ims.tsukuba.ac.jp (H. Y. Kim),miyazaki@ims.tsukuba.ac.jp (S. Miyazaki).The effects of Sn content on stress hysteresis and superelastic properties of Ti-15Nb-3Mo-(0-1.5)Sn were investigated. The stress hysteresis decreased with increasing Sn content due to the suppression of athermal omega phase formation. The addition of Sn was also very effective for increasing superelastic recovery strain. Dueto a two-fold role of Sn, i.e. on the martensitic transformation temperature and omega phase, the stress for inducing martensitic transformation decreased with increasing Sn content up to 1at.%, then increased by further addition.Keywords: Titanium alloys; Shape memory alloys; SuperelasticityTi-Ni alloys have been successfully utilized in various biomedical devices due to their exceptional superelastic properties. The major biomedical applications of Ti-Ni alloys have been found in devices such as stents, guide wires and dental arch wires [1]. However, despite their excellent superelastic performance and successful safe usage for medical applications, there are still concerns over the high concentration of Ni in various Ti-Ni-based superelastic alloys. Therefore efforts have been devoted to develop new classes of Ni-free Ti-based superelastic alloys [2-8]. Among them, Ti-Nb-based alloys have been able to get significant attention [7-13]. Superelasticity in Ti-Nb-based alloys is attributed to the reversible stress-induced martensitic transformation between parent βphase (bcc) and martensite α" phase (orthorhombic structure) [14, 15]. Superelastic recovery strain is primarily dependent on the transformation strain which is determined by the crystal structures of parent phase and martensite phase. Recently our group reported that the addition of Mo to Ti-Nb alloys is very effective to increase superelastic recovery strain due to the solid solution strengthening effect of Mo and the increase in transformation strain [16]. However, excess addition of Mo for the replacement of Nb in Ti-Nb-Mo alloy system deteriorates superelastic properties mainly due to the formation of a large amount of athermal ω phase [16]. It was also reported that the increase in Mo content significantly increases the stress hysteresis of Ti-Nb-Moalloys [17]. A small stress hysteresis is preferable for superelastic alloys to take advantage of a high recovery force. In this study, we show that the addition of Sn is very effective not only to reduce stress hysteresis but also to improve superelastic recovery strain of a Ti-Nb-Mo alloy. The unique Sn content dependence of the critical stress for inducing martensitic transformation in Ti-15Nb-3Mo alloys is analyzed by microstructural observation.Ti-15Nb-3Mo-(0-1.5)Sn (at.%) (all compositions are hereafter described in atomic per cent) ingots were prepared by arc-melting in an Ar atmosphere. The ingots were homogenized at 1273 K for 7.2 ks followed by cold-rolling up to 98.5% reduction in thickness without intermediate annealing. Specimens for tensile tests, X-ray diffraction (XRD) measurements and transmission electron microscope (TEM) observation were cut from the as-rolled strips using an electric discharge cutting machine. All the specimens were heat-treated at 973 K for 0.6 ks in an Ar filled quartz tube, followed by quenching in water. Superelastic properties were characterized by loading-unloading tensile tests at room temperature (298 K). The dimensions of the tensile specimens were 0.14 mm in thickness and 1.5 mm in width, with a length of 40 mm. Tensile tests were performed using a Shimadzu Autograph 5KN tensile testing machine at a cross-head speed of 2.5 х 10-4 s-1. Both ends of the tensile specimens were fixed with in two chucks so that gage length becomes 20 mm and the strain of the specimens was determined by measuring the distance between the chucks using an extensometer. Constituent phases were investigated using an XRD machine with a Cu Kαradiation source. Microstructural analysis was conducted by TEM, using a JEOL 2010F microscope operated at 200 kV.Figure 1a shows stress–strain curves of Ti-15Nb-3Mo-(0-1.5)Sn alloys obtained at room temperature. The specimen was elongated until reaching 2.5% strain and then unloaded. All the alloys exhibited superelastic recovery. A single headed arrow points at the critical stress required for inducing martensitic transformation (σβ→α"), whereas a double head arrow points at the stress where the reverse transformation finishes (σα"→β) upon unloading. Stress hysteresis (∆σ) was defined as the difference between σβ→α" and σα"→β.The Sn content dependences of σβ→α" and σα"→βare shown in Figure 1b. So far, it has been reported that Sn decreases M s of Ti-Nb based alloys [18, 19]. Therefore, it is expected that σβ→α"increases with increasing Sn content, since the stress for inducing martensitic transformation at a fixed test temperature increases with decreasing M s of the alloy. However, Figure 1b shows a peculiar Sn content dependence of σβ→α": it decreased by the addition of Sn up to 1 at.%, and then increased by further addition. This implies that the addition of Sn up to 1 at.% raised M s of the Ti-15Nb-3Mo alloy, but further addition caused the decrease of M s. On the other hand, σα"→β exhibited a monotonic increasing tendency with the increase in Sn content as shown in Figure 1b. It is important to note that the addition of Sn causes a significant decrease in ∆σof the Ti-15Nb-3Mo alloy. It is apparent that the decreasing trend of ∆σ is more pronounced particularly up to 1 at.% Sn addition as shown in Figure 1c.In order to investigate superelastic properties of the Ti-15Nb-3Mo-(0-1.5)Sn alloys, cyclic loading–unloading tensile tests were carried out and the results are shownin Figure 2. In the first cycle, the tensile stress was applied until the strain reached 1.5% and then unloaded. The similar measurement was repeated by increasing maximum strain by the interval of 0.5% (such as 1.5 %, 2.0% for each successive cycle of loading) using the same specimen. In order to evaluate superelastic properties, two types of strain, i.e. recovery strain (εr) and remained plastic strain (εp) were measured at each cycle. It is seen that the strain was almost totally recovered upon unloading up to the first cycle for Ti-15Nb-3Mo, up to the third cycle for Ti-15Nb-3Mo-0.5Sn and Ti-15Nb-3Mo-0.75Sn, up to the fourth cycle for Ti-15Nb-3Mo-1Sn and Ti-15Nb-3Mo-1.25Sn, and up to the first cycle for Ti-15Nb-3Mo-1.5Sn, respectively. The magnitudes of maximum recovery strain εr max, σβ→α" and ∆σ are listed in Table 1. Interestingly, these properties, i.e. εr max, σβ→α"and ∆σshow different Sn content dependences. As mentioned above, with increasing Sn content σβ→α"decreased to minimum at Ti-15Nb-3Mo-1Sn and it was then increased by further addition of Sn. On the other hand, ∆σ exhibited a monotonic decreasing tendency with increasing Sn content. The decrease in the stress hysteresis caused the increase in the superelastic recovery strain; εr max increased to a maximum value of 3.7% at Ti-15Nb-3Mo-1.25Sn. However Ti-15Nb-3Mo-1.5Sn exhibited a small recovery strain of 2.1% in spite of its smallest stress hysteresis. It is suggested that the small recovery strain of Ti-15Nb-3Mo-1.5Sn is due to its high σβ→α". A high σβ→α"reduces the difference between the critical stress for permanent plastic deformation and the stress for inducing martensitic transformation, resulting in that the permanent plastic deformation occurs during the martensitic transformation.In order to discuss the effect of Sn content on superelastic properties, XRD measurement and TEM observation were carried out. Figure 3a shows XRD profiles of the Ti-15Nb-3Mo-(0-1.5)Sn alloys obtained at room temperature. Within the measured 2θ (deg.) range, β phase was identified by four major reflections from (110)β, (200)β, (211)β, and (222)βwhereas ωphase was identified by two major reflections from (001)ω and (002)ω. The reflections from the ω phase are found to be sensitive to the Sn content. It is clearly seen that the Ti-15Nb-3Mo alloy reveals the strongest intensity of the ωphase. The ωphase is suggested to be formed athermally during quenching from the annealing temperature (973 K). The peak intensities of the ω phase gradually became weaker as the Sn content increased. The peaks from the ωphase could not be detected in the XRD profiles of the Ti-15Nb-3Mo-1.25Sn and Ti-15Nb-3Mo-1.5Sn alloys. This implies that the ω phase was suppressed significantly with the increase in Sn content, which is consistent with previous works [20, 21]. The suppression of athermal omega phase (ωath) by the addition of Sn was also confirmed by TEM observation. Figure 3b shows dark-field images and the corresponding selected area diffraction patterns with zone axis of [113]βin the Ti-15Nb-3Mo and Ti-15Nb-3Mo-1Sn alloys. Dark-field images showing the ω phase were formed using the diffraction spot indicated by a white circle in each diffraction pattern. It is seen that the size and volume fraction of the ωath phase were remarkably reduced by the Sn addition.On the basis of microstructure analysis, the unique Sn content dependences of σβ→α"and stress hysteresis in the Ti-15Nb-3Mo-(0-1.5)Sn alloys can be explained by considering a two-fold role of Sn; the one hand Sn decreases M s of Ti-Nb based alloys, on the other hand it suppresses the ω phase formation. It has been confirmed that the athermal ωphase suppresses the martensitic transformation and increases in σβ→α"of Ti-Nb-Mo alloys [16, 17], implying that the suppression of the athermal ωphase increases M s. Figure 4 illustrates the schematic explanation of the effect of Sn on apparent M s and σβ→α". If we only consider the compositional effect, σβ→α"should increase monotonically with increasing Sn content because the difference between M s and test temperature (RT) increases. However, a large amount of athermal ω phase in the Ti-15Nb-3Mo alloy decreases M s and increases σβ→α"of the alloy. As mentioned above, the volume fraction of athermal ω phase decreases with increasing Sn content, indicating that the decrease in M s due to the ωphase is reduced as the Sn content increases. Consequently the decrease in σβ→α" with increasing Sn content up to 1 at.% in the Ti-15Nb-3Mo-(0-1.5)Sn alloys implies the fact that the effect of Sn on the suppression of athermal ωphase is stronger than the compositional effect which decreases M s. As the Sn content increased the effect of Sn on the suppression of athermal ω phase becomes weaker, hence the compositional effect becomes dominant. This explains why σβ→α" increases with increasing Sn content from 1 at.% to 1.5 at.%.On the other hand, the monotonic increase in σα"→β with increasing Sn content suggests that the intrinsic compositional effect of Sn is dominant for the reverse transformation. It has been proposed that the athermal ω phase also transforms into the α" phase when the β phase transforms [17, 22]. As a result, according to the current understanding, it is believed that the monotonic change in σα"→β is mainly attributed to the absence of the ωphase in the α" phase while unloading. This explains not only a large stress hysteresis loop in the ternary alloy but also the decrease of stress hysteresis with increasing Sn content.In conclusion, we are able to reduce the stress hysteresis and increase the superelastic recovery strain of a Ti-Nb-Mo alloy by the addition of Sn. The decrease in the stress hysteresis with increasing Sn content is due to the suppression of the athermal ωphase. The unique Sn content dependence of the critical stress for inducing martensitic transformation in Ti-15Nb-3Mo-(0-1.5)Sn alloys is due to a two-fold role of Sn, i.e. the decrease of M s and the suppression of the athermal ω phase.AcknowledgmentsThis work was partially supported by JSPS KAKENHI Grant Number 23360300 and 25289247, MEXT KAKENHI Grant Number 23102503 and 25102704.References[1] T. Yoneyama, S. Miyazaki, Shape Memory Alloys for Biomedical Applications, Woodhead Publishing, Cambridge, 2009.[2] S. Miyazaki, H.Y. Kim, H. Hosoda, Mater. Sci. Eng. A 438-440 (2006) 18.[3] H.Y. Kim, S. Hashimoto, J.I. Kim, T. Inamura, H. Hosoda, S. Miyazaki, Mater. Sci. Eng. A 417 (2006) 120.[4] T.W. Duerig, J. Albrecht, D. Richter, P. Fischer, Acta Metall. 30 (1982) 2161.[5] L.C. Zhang, T. Zhou, S.P. Alpay, M. Aindow, Appl. Phys. Lett. 87 (2005) 241909.[6]T. Maeshima, M. Nishida, Mater. Trans. 45 (2004) 1101.[7]M. Niinomi, T. Akahori, S. Katsura, K. Yamauchi, M. Ogawa, Mater. Sci. Eng. 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(a) XRD profiles for Ti-15Nb-3Mo-(0-1.5)Sn alloys and (b) dark field images and the corresponding selected area diffraction patterns for Ti-15Nb-3Mo and Ti-15Nb-3Mo-1Sn alloys.Figure 4. A schematic explanation on the effect of Sn on Ms and σβ→α".Figure 1.(a) Stress-strain curves of Ti-15Nb-3Mo-(0-1.5) Sn alloys, (b) effect of Sn content on σβ→α" and σα"→β and (c) effect of Sn content on stress hysteresis ∆σ.Figure 2.Stress-strain curves obtained by cyclic loading–unloading tensile tests for Ti-15Nb-3Mo-(0-1.5) Snalloys.alloys and (b) dark field images and the corresponding selectedarea diffraction patterns of Ti-15Nb-3Mo and Ti-15Nb-3Mo-1Sn alloys.and σβ→α".Table 1.Summary of superelastic properties obtained by cyclic loading-unloading tensile tests of Ti-15Nb-3Mo-(0-1.5)Sn alloys.Alloy (at.%)σβ-α″(MPa)∆σ(MPa)εr max(%)Ti-15Nb-3Mo-0Sn297 253 2.1 Ti-15Nb-3Mo-0.5Sn259 212 3.1 Ti-15Nb-3Mo-0.75Sn252 172 3.2 Ti-15Nb-3Mo-1Sn212 123 3.3 Ti-15Nb-3Mo-1.25Sn271 121 3.7 Ti-15Nb-3Mo-1.5Sn344 78 2.1。
