CAREER: Neutron, Synchrotron X-ray Diffraction and Instrumented Indentation Studies of Deformation in Shape-Memory Alloys

形状记忆合金具有孪晶、应力诱导相变和温度诱导相变等形变现象，因此具有重要的理论和商业价值。建议的程序使用中子衍射，同步辐射X射线衍射和仪器化压痕，以调查形状记忆合金的变形。重点是原位衍射测量，即，同时记录来自经受外部应力或温度变化或其组合的样品的衍射光谱。这种测量提供了在孪生和应力诱导或温度诱导相变过程中演变的内部应变、织构和相体积分数的定量信息。实验将利用洛斯阿拉莫斯国家实验室的中子束和阿贡国家实验室的同步加速器X射线束。与研究形状记忆合金中的变形的主题和从形状记忆合金的小取样体积获得机械性能的目标相一致，将在形状记忆合金上进行仪器化压痕实验，以将压痕实验的载荷-深度数据与常规试验的宏观应力-应变数据相关联。该计划预计将进一步理解（a）形状-用于致动器应用和用于生物医学应用的记忆合金，因为形状记忆合金继续作为支架的选择材料取得进展，以及（B）中子衍射、同步加速器X射线衍射和仪器化的微米和纳米压痕作为新兴材料、块体、涂层、薄膜、线和点形式中的内应力的机械表征的有价值的工具。教育活动包括课程编制、教学和实验室开发，为学生使用国家实验室的设施提供经验和培训。推广和指导活动包括与当地科学中心和少数民族工程和计算机科学办公室在UCF，工程教育在工作场所通过远程教育在佛罗里达工程教育交付系统（FEEDS）和行业短期课程的发展合作。

Shape-memory alloys are of theoretical and commercial interest for the deformation phenomena they exhibit - twinning and stress-induced or temperature-induced phase transformations. The proposed program uses neutron diffraction, synchrotron X-ray diffraction and instrumented indentation to investigate deformation in shape-memory alloys. The emphasis is on in situ diffraction measurements, i.e., simultaneously recording diffraction spectra from samples that are subjected to external stresses or temperature changes, or a combination thereof. Such measurements provide quantitative information of the evolving internal strains, texture and phase volume fractions during twinning and stress-induced or temperature-induced phase transformations. The experiments will utilize the neutron beam at Los Alamos National Laboratory and the synchrotron X-ray beam at Argonne National Laboratory. Consistent with the theme of investigating deformation in shape-memory alloys and with the objective of obtaining mechanical properties from small sampling volumes of shape-memory alloys, instrumented indentation experiments will be performed on shape-memory alloys to correlate load-depth data from indentation experiments with macroscopic stress-strain data from conventional tests.The program is expected to further the understanding of (a) shape-memory alloys for actuator applications and for biomedical applications, as shape-memory alloys continue to make inroads as the material of choice for stents, and (b) neutron diffraction, synchrotron X-ray diffraction and instrumented micro- and nanoindentation as valuable tools for mechanical characterization of internal stresses in emerging materials, bulk, coatings, thin-films, line and dot forms. The educational activities include curriculum development, instruction and laboratory development providing experience and training for students using facilities at National Laboratories. Outreach and mentoring activities include collaboration with a local science center and the Minority Engineering and Computer Science Office at UCF, engineering education in the work place through distance education in the Florida Engineering Education Delivery System (FEEDS) and the development of industry short-courses.