Thermodynamics and Phase Equilibria of Heusler and half-Heusler Alloys

霍斯勒合金和半霍斯勒合金的热力学和相平衡

• 批准号: 0964812
• 负责人: Philip Nash
• 金额: $ 33.32万
• 依托单位: Illinois Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0964812&HistoricalAwards=false
• 关键词: Thermodynamics; Phase; Equilibria; Heusler; half

TECHNICAL SUMMARY: Heusler compounds of type A2BC and 'half-Heusler' compounds of type ABC, where A and B are transition metals and C is a group III-V element are of great interest for their functional properties such as shape memory, thermoelectric, ferromagnetic and spin polarization effects which could lead to new mechanical and electronic devices. The objectives of the proposed research are to accurately determine heats of formation for ternary compounds of this type, to make complementary measurements of heat capacity, phase equilibria, melting points and lattice parameters and to analyze these data to provide understanding of the systematic alloying behavior in these systems. The enthalpies of formation of the compounds will be determined by direct synthesis reaction calorimetry using a Kleppa type calorimeter. The specific heats will be determined over a range of temperature from enthalpy measurements made in a Setaram high temperature drop calorimeter. Although potentially there are 230 compounds, rapid screening of composition space to identify which systems contain these compounds will be performed using diffusion multiples and systematic analysis of phase diagrams. The thermodynamic data obtained will be incorporated into an on-line database for access by the scientific community. The data will be incorporated in computational thermodynamic Gibbs energy descriptions of the compounds for use in predicting phase equilibria. Such data are also of importance in providing benchmarks for first principles calculations and for optimization of thermodynamic descriptions of compounds to permit future computational alloy development extending to higher order systems.NON-TECHNICAL SUMMARY: Novel mechanical and electronic devices may be possible using compounds based on three metallic elements. These compounds often exhibit properties such as magnetic or thermal shape memory and large shape change in magnetic fields which can be used for mechanical actuators and half metal-half semiconductor property which can be used to produce so-called 'spintronic' devices or conversion of thermal energy to electrical energy which have the potential to reduce energy consumption and waste heat loss in electronic devices. Basic property measurements will be made on a large number of such compounds, many of which have not been synthesized previously. The results of this project can be used by the wider scientific community for further alloy development of these materials and application to devices. Graduate and undergraduate students and high school students from the Illinois Mathematics and Science Academy will be directly involved in the research. Laboratory tours will be arranged for 3-8th grade classes from a local Chicago public school. The project involves a substantial international collaboration with researchers in both China and Korea and will provide opportunity for researchers to visit IIT to give seminars to our students and interact with faculty and graduate students. The thermodynamic database is available for all scientists to access via the web. Video tutorials of experimental techniques will be produced, edited and made available on the web as well as through iTunes U.

技术概要：A2 BC型Heusler化合物和ABC型“半Heusler”化合物（其中A和B是过渡金属，C是III-V族元素）因其功能性质（例如形状记忆、热电、铁磁和自旋极化效应）而受到极大关注，这些功能性质可导致新的机械和电子器件。拟议的研究的目标是准确地确定这种类型的三元化合物的形成热，使热容量，相平衡，熔点和晶格参数的补充测量，并分析这些数据，以提供在这些系统中的系统合金化行为的理解。化合物的形成速率将使用Kleppa型量热计通过直接合成反应量热法测定。比热将在一定温度范围内由Setaram高温降热量计中进行的焓测量确定。虽然可能有230种化合物，但将使用扩散倍数和相图的系统分析来快速筛选组成空间以确定哪些系统含有这些化合物。所获得的热力学数据将纳入一个联机数据库，供科学界查阅。这些数据将被纳入计算热力学吉布斯能描述的化合物用于预测相平衡。这样的数据也是重要的，在提供基准的第一原理计算和优化的热力学描述的化合物，以允许未来的计算合金发展延伸到更高阶system.Non-Technical摘要：新的机械和电子设备可能使用基于三种金属元素的化合物。这些化合物通常表现出诸如磁或热形状记忆和磁场中的大形状变化的性质，其可用于机械致动器，以及半金属-半半导体性质，其可用于生产所谓的“自旋电子”器件或将热能转化为电能，其具有降低电子器件中的能量消耗和废热损失的潜力。将对大量此类化合物进行基本性质测量，其中许多化合物以前没有合成过。该项目的结果可被更广泛的科学界用于这些材料的进一步合金开发和器械应用。来自伊利诺伊州数学和科学学院的研究生、本科生和高中生将直接参与这项研究。将为当地芝加哥公立学校的3- 8年级班级安排实验室图尔斯参观。该项目涉及与中国和韩国研究人员的大量国际合作，并将为研究人员提供访问IIT的机会，为我们的学生举办研讨会，并与教师和研究生互动。热力学数据库可供所有科学家通过网络访问。将制作、编辑实验技术的视频教程，并在网上和iTunes U上提供。