SGER: Magnetic Shape Memory Behavior in New Materials

新材料中的磁性形状记忆行为本文提出的工作对于理解一种非常有前途的铁磁形状记忆合金系统的磁机械响应具有高度的优先性。研究的重点是在外加磁场作用下发生形状变化的锥形合金。铁磁形状记忆合金在外加磁场作用下发生马氏体变异体结构的重排，产生的应变只有百分之几。与传统的形状记忆合金相比，它们具有响应时间更快的优势，并且与其他铁磁形状记忆材料相比，CoNiAl具有更高的强度。实验包括测量两种特定成分CoNiAl合金的磁化强度与外加磁场的关系，通过测试几种晶体取向建立易磁化轴和硬磁化轴，以及测量磁场诱导应变随外加应力的函数。通过应力下的温度循环和形状记忆行为的观察来评估CoNiAl合金的力学响应。这项工作将对新材料的设计及其建模产生影响，并在各种工程设备（如执行器）中有潜在的应用。该项目将提供一个机会，培养研究生和本科生了解转化材料，铁磁性和形状记忆行为的基本概念。

Magnetic Shape Memory Behavior in New MaterialsThe proposed work represents a high priority in understanding the magneto-mechanical response of a very promising ferromagnetic shape memory alloy system. The focus is on CoNiAl alloys that undergo shape change associated with applied magnetic fields. Ferromagnetic shape memory alloys undergo rearrangement of the martensitic variant structure under an applied magnetic field which could produce few percent strains. They have advantages over traditional shape memory alloys because of their faster response time, and the CoNiAl has higher strength compared to other ferromagnetic shape memory materials. The experiments include measurement of magnetization versus applied magnetic field for two specific compositions of CoNiAl alloys, the establishment of easy and hard axis of magnetization with testing of several crystal orientations, and the magnetic field induced strain measurements as a function of applied stress. The mechanical response of the CoNiAl alloys will be also evaluated via temperature cycling under stress and observation of the shape memory behavior. The work will have impact in design of new materials and their modeling, and potential applications in various engineering devices such as actuators. The project will provide an opportunity to train a graduate student as well as undergraduate students in understanding the fundamental concepts in transforming materials, ferromagnetism and shape memory behavior.