CAREER: Shear Localization in Metallic Glasses

关于剪切带的形成有各种各样的理论。这些模型假设原子尺度结构的变化与剪切带的起始有关，因此应该有可能通过适当的结构表征来验证它们。本项目包括一系列的透射电子显微镜（TEM）和扩展能量损失精细结构（EXELFS）实验，旨在：(a)确定与剪切带形成相关的原子尺度结构变化，以阐明剪切带形成的机制；(b)表征剪切带与第二相粒子的相互作用，考察粒子对剪切带成核和运动的影响。结构观测结果与准静态力学试验结果相关联。职业发展计划将这些研究目标与高中生、本科生和研究生的教育以及当地高中科学教师的专业发展相结合。这是通过为处于经济和社会风险中的高中生开发一个密集的、信息丰富的、娱乐的两周暑期项目来实现的。夏季课程侧重于在运动器材中使用创新材料，并强调广泛的师生互动，与研究小组成员的互动，实践经验和团队合作。通过比较目前使用的材料与新材料（大块金属玻璃）的相关性能，学生和老师将了解材料的选择过程，并了解如何将材料的基础科学进展转化为实用技术。它将为教师提供与现代技术相关的材料范例，为示范和实验提供有用的思路，并为进一步的专业发展提供在大学的联系。大块玻璃成形合金的最新发展为金属玻璃开辟了一个新的工程应用范围。金属玻璃现在可用于其独特的机械性能有利的应用领域。这些发展突出了对金属玻璃永久变形的基本机制的进一步了解的必要性

9875115HufnagelThere are variety of theories regarding the initiation of shear bands. These models postulate changes in atomic-scale structure associated with the initiation of a shear band, so it should be possible to verify them by appropriate characterization of the structure. This project involves a series of transmission electron microscopy (TEM) and extended energy loss fine structure (EXELFS) experiments designed to: (a) identify the atomic-scale structural changes associated with shear band formation with the goal to elucidate the mechanisms of shear band formation; and (b) characterize the interactions of shear bands with second-phase particles, examining the effect of particles on both shear band nucleation and motion. Structural observations are correlated with the results of quasi-static mechanical testing. The career development plan integrates these research goals with the education of high school, undergraduate, and graduate students as well as professional development of local high school science teachers. This is achieved by developing an intensive, informative and entertaining two-week summer program for economically and socially at-risk high school students. The summer program focuses on the use of innovative materials in sports equipment, and emphasizes extensive student-teacher interaction, interaction with the members of the research group, hands-on experience, and teamwork. By comparing the relevant properties of currently-used materials with new materials (bulk metallic glasses), the students and teachers will gain an appreciation for the materials selection process and see how fundamental scientific advances in materials can be converted into practical technology. It will provide the teachers with relevant examples of materials in modern technology, useful ideas for demonstrations and experiments, and contacts in the university for further professional development.%%%The recent development of bulk glass-forming alloys has opened up a new range of engineering applications for metallic glasses. Metallic glasses may now be employed in applications where their unique mechanical properties are advantageous. These developments have highlighted a need for an improved understanding of the fundamental mechanisms of permanent deformation of metallic glasses***