CAREER: Interface Deformation and Compatibility in Shape Memory Polycrystals

技术概述：形状记忆合金（sma）是一种独特的多功能相变材料。它们可以在热循环或机械循环下通过可逆马氏体相变在两种形状之间切换，并且在传感，驱动，能量转换和收集以及阻尼方面有很好的应用前景。这个CAREER项目连接了迄今为止两个独立的研究领域，(i)晶界科学与工程和（ii） SMA中的位移马氏体相变，并试图理解双相SMA多晶马氏体相变过程中界面间的机械相互作用。本研究将采用实验、分析理论和中尺度计算模型来探讨两种主要的界面效应：(1)晶界晶体学特征对晶界应变传递、调节和相容性的影响；(2)沿晶界析出的非相变延展性相如何适应来自跨相界的相变应变。将探索晶界工程，增强晶界应变相容性，从而提高SMA多晶的延展性和适用性。本研究获得的对界面应变传递和相容性的基本理解也将与许多其他多晶金属和化合物的类似问题相关。非技术概述：形状记忆合金（sma）是一种独特的多功能材料。它们可能沿内部平面缺陷或称为晶界的界面发生脆性断裂，这一问题极大地限制了它们的适用性。本项目将通过实验表征和计算建模定量阐明sma失效的机制。这项工作还将利用晶界工程策略来改善sma的晶界性能并增强其延展性，这将使sma在商业和军事领域的先进技术中的实际应用成为可能。这个项目还将涉及大量的教育和外联工作。教育活动包括转变本科生和研究生的核心力学性能课程，为计算材料课程做出贡献，培养本科生和研究生成为机械性能、金属和计算材料科学的专家和领导者的研究人员。外展活动将吸引年轻学生对科学和工程的兴趣，提高公众对工程的兴趣，并支持女性工程专业学生的专业发展和进步。

Technical Summary:Shape Memory Alloys (SMAs) are unique multifunctional phase-change materials. They can switch between two shapes under thermal or mechanical cycling by a reversible martensitic phase transformation, and are promising for applications in sensing, actuation, energy conversion and harvesting, and damping. This CAREER project bridges two thus far separate research areas, (i) grain boundary science and engineering and (ii) displacive martensitic transformations in SMAs, and seeks to understand mechanical interactions across interfaces during martensitic transformations in dual-phase SMA polycrystals. This research will use experiments, analytical theory, and mesoscale computational modeling to explore two major interface effects: (1) the effects of grain boundary crystallographic character on strain transfer, accommodation, and compatibility at grain boundaries; (2) how a non-transforming, ductile phase precipitated along grain boundaries accommodates transformation strains from across phase boundaries. Grain boundary engineering will be explored to enhance strain compatibility at grain boundaries, thereby improving the ductility and applicability of SMA polycrystals. The fundamental understanding on strain transfer and compatibility at interfaces gained in this research will also be relevant to similar problems in many other polycrystalline metals and compounds. Non-Technical Summary:Shape Memory Alloys (SMAs)are unique multifunctional materials. They can fail by brittle fracture along internal planar defects or interfaces called grain boundaries and this problem has significantly limited their applicability. This project will quantitatively elucidate the mechanisms for failure in SMAs by performing experimental characterizations and computational modeling. This work will also exploit grain boundary engineering strategies to improve grain boundary properties and enhance the ductility of SMAs, which will enable practical applications of SMAs in advanced technologies in both commercial and military sectors. This project will also involve substantial education and outreach efforts. The education activities include transforming both undergraduate and graduate core mechanical properties courses, contributing to computational materials course, and training undergraduate and graduate researchers who will become experts and leaders in mechanical properties, metals, and computational materials science. The outreach activities will attract young students to science and engineering, promote public interest in engineering, and support professional development and advancement of women engineering students.