Domain Mechanisms in Magnetic Shape Memory Alloys

该奖项支持理论和计算研究和教育，旨在推进对磁形状记忆合金领域现象的基本理解，以及用于传感器、执行器、换能器和能量收集的其他技术上重要的多功能材料。畴通常是材料内部的微小区域，但仍然包含许多原子，这些原子以相同的方式组织自己，例如具有相同的结构或相同的磁取向，但在邻近的畴中组织不同。涉及域的物理过程负责这些材料的特性，使它们对特定应用有用，它们的功能。PI将结合互补的领域级计算和实验方法来研究复杂磁性材料中的领域现象，旨在建立材料特性和领域过程之间的联系。这项研究将为材料科学的研究生提供培训，并为本科生创造研究机会和经验。研究成果为计算材料学和材料物理行为的教学提供了有价值的现实启发实例。PI将参与密歇根理工大学现有的推广活动，在高中生、妇女和代表性不足的少数民族中推广材料科学和工程。该奖项支持理论和计算研究和教育，旨在推进对磁性形状记忆合金和其他技术上重要的多功能材料领域现象的基本理解。磁性形状记忆合金能对外界的磁、机械和热刺激作出积极反应，并能进行能量转换。磁形状记忆合金的功能源于磁畴和弹性畴的耦合微观结构的演变，这导致了丰富的畴现象和复杂的物理行为，对基础科学和技术应用具有重要意义。PI旨在建立宏观性质与内部域过程之间的相关性，确定潜在的域机制，并找到优化域微观结构和控制其演化路径的有效方法，以定制有用的性质。该项目涉及磁和弹性耦合域过程的定量研究，通过使用相场微磁微弹性方法进行域级建模和模拟，以及使用干涉对比胶体技术进行原位域观测实验，解决重要的域机制。特别地，PI将关注(i)磁致伸缩，（ii）双边界迁移率，（iii）磁易方向，以及（iv）纳米尺度结构非均质性对畴过程和由此产生的场致变形行为的影响。这些效应决定了磁弹性的性质，但是它们的作用还没有被阐明。本研究的目标是：(1)开发计算工具来进行区域微观结构演变的仿真研究；(2)开展协同地域观测实验；(3)识别控制磁弹性行为的重要域机制；(4)促进对畴过程的基本理解，并为性能改进和新材料开发提供见解；(5)将研究整合到PI在功能材料和计算材料科学方面的教育和推广活动中。

NONTECHNICAL SUMMARYThis award supports theoretical and computational research and education that is aimed to advance fundamental understanding of domain phenomena in magnetic shape memory alloys as well as other technologically important multifunctional materials for applications in sensors, actuators, transducers, and energy harvesting. Domains are usually tiny regions inside of materials but still contain many atoms that have organized themselves in the same way, for example with the same structure or same magnetic orientation, but are organized differently in neighboring domains. Physical processes involving domains are responsible for the properties of these materials that make them useful for a particular application, their functionality. The PI will combine complementary domain-level computational and experimental approaches to investigate domain phenomena in complex magnetic materials with an aim to establish connections between materials properties and domain processes. The research will provide training for a graduate student in materials science, and creates research opportunities and experiences for undergraduates. The research outcomes provide valuable real-world inspired examples for teaching computational materials science and physical behaviors of materials in courses. The PI will participate in existing outreach activities at Michigan Technological University to promote materials science and engineering among high school students, women and underrepresented minorities.TECHNICAL SUMMARYThis award supports theoretical and computational research and education that is aimed to advance fundamental understanding of domain phenomena in magnetic shape memory alloys and other technologically important multifunctional materials. Magnetic shape memory alloys actively respond to external magnetic, mechanical, and thermal stimuli, and are capable of energy conversion. Magnetic shape memory alloy functionalities originate from the evolution of coupled magnetic and elastic domain microstructures, which leads to rich domain phenomena and sophisticated physical behaviors that are important for both basic science and technological applications. The PI seeks to establish correlations between macroscopic properties and internal domain processes, identify underlying domain mechanisms, and find effective ways to optimize the domain microstructures and control their evolution pathways to tailor the useful properties. This project involves the quantitative investigation of coupled magnetic and elastic domain processes to address important domain mechanisms by domain-level modeling and simulations using phase-field micromagnetic microelastic methods and in-situ domain observation experiments using an interference-contrast-colloid technique. In particular, the PI will focus on the effects of (i) magnetostriction, (ii) twin boundary mobility, (iii) magnetic easy direction, and (iv) nanoscale structural heterogeneity on domain processes and the resultant field-induced deformation behaviors. These effects determine magnetoelastic properties, but their roles are yet to be clarified. The objectives of the research are to: (1) develop computational tools to perform realistic simulation studies of domain microstructure evolutions; (2) carry out coordinated in-situ domain observation experiments; (3) identify important domain mechanisms governing magnetoelastic behaviors; (4) advance fundamental understanding of domain processes and provide insight into property improvement and guidance for new materials development; and (5) integrate the research into the PI's educational and outreach activities in functional materials and computational materials science.