NSF-Europe: U.S. - Germany Research Collaboration: "Bridging Length Scales in Deforming Single and Textured Polycrystals of Structural Magnetic Shape Memory Alloys"

该基金探索了从粉末前驱体和单晶生长中制备纹理FeNiCoTi和CoNiAl磁性形状记忆合金（MSMA）多晶的方法。主要目的是表征微观结构，物理和磁热机械（MTM）行为，以便更好地理解磁，热和机械诱导msma应变的机制。随着实验研究的进行，建模工作将考虑外磁场和纹理。粉末将通过高压气体雾化制备，通过施加磁场沿易磁化轴定向，并通过热等通道角挤压（ECAE）和热等静压巩固。除了应力、温度和磁场下的力学测试外，还计划使用原位透射电镜和取向成像显微镜进行微观结构表征，使用量热法和x射线衍射进行物理表征。金属粉末的固化和sma的建模将在德克萨斯a&m大学进行，而热力学表征将与在活性粉末上具有丰富经验的帕德博恩大学合作进行。与传统的sma（如NiTi）相比，有纹理的MSMA多晶的创新处理有望带来高场致驱动力水平，所需的磁激活微观结构形态以及更高的响应频率。建议的研究将有助于促进制造和使用sma和磁性材料用于工程的当地文化。这不仅是通过在与德国学生和研究人员合作的环境中教育直接参与该项目的研究生和本科生，而且还通过在当前的课堂活动中建立演示和实验室实验来实现。研究人员计划利用拟议的研究来帮助开发一门新的研究生水平的活性材料课程。德州农工大学的其他推广和教育活动将用于向K-12数学和科学教师以及来自不同背景的在读高中生传播所获得的知识。***本项目由多学科活动办公室、材料研究部（金属研究）和国际办公室（西欧）共同资助，作为美国国家科学基金会与欧洲材料研究合作项目（NSF 02-135）。该项目是与德国帕德博恩大学合作进行的。

The grant explores fabrication of textured FeNiCoTi and CoNiAl magnetic shape memory alloy (MSMA) polycrystals from powder precursors and single crystal growth. A major objective is to characterize the microstructural, physical and magneto-thermo-mechanical (MTM) behavior for better understanding of the mechanisms responsible for magnetically, thermally and mechanically induced strains in MSMAs. Along with the experimental studies, modeling effort will take into account the external magnetic field and texturing. The powders will be prepared by high-pressure gas atomization, oriented along the easy magnetization axis by application of a magnetic field and consolidated by warm equal channel angular extrusion (ECAE) and hot isostatic pressing. Along with mechanical testing under stress, temperature as well as magnetic field, microstructural characterization is planned with in-situ transmission electron microscopy and orientation imaging microscopy, and physical characterization with calorimetry and X-Ray diffraction. The consolidation of metallic powders and modeling of SMAs will be performed at Texas A&M University while thermomechanical characterization will be performed in collaboration with the University of Paderborn with extensive experience on such activities on active powders. The innovative processing of the textured MSMA polycrystals are expected to lead to high field-induced actuation force levels, desired microstructural morphology for magnetic activation, and higher response frequencies compared to conventional SMAs such as NiTi.%%%The proposed research will help to foster local culture of fabricating and using SMAs and magnetic materials for engineering. This will come about not only by educating graduate and undergraduate students directly involved in this project in a collaborative environment with German students and researchers but also by building demonstrations and laboratory experiments into current classroom activities. The investigators plan to use the proposed research to aid in the development of a new graduate-level course on active materials. Other outreach and education activities at Texas A&M will be used to disseminate knowledge gained to mathematics and science K-12 instructors and current high school students from diverse backgrounds. ***This NSF project is co-funded by the Office of Multidisciplinary Activities, the Division of Materials Research (Metals Research) and International Office (Western Europe) as a Cooperative Activity in Materials Research between the NSF and Europe (NSF 02-135). This project is being carried out in collaboration with University of Paderborn in Germany.