CAREER: Shear Localization in Metallic Glasses

职业：金属玻璃中的剪切局部化

• 批准号: 9875115
• 负责人: Todd Hufnagel
• 金额: $ 32.5万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-15 至 2004-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9875115&HistoricalAwards=false
• 关键词: CAREER; Shear; Localization; Metallic; Glasses

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***

9875115 Hufnagel关于剪切带的形成有多种理论。 这些模型假定了与剪切带的形成相关的原子尺度结构的变化，因此应该可以通过适当的结构表征来验证它们。 该项目包括一系列透射电子显微镜（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，目的是阐明剪切带形成的机制;和（B）表征剪切带与第二相颗粒的相互作用，检查颗粒对剪切带成核和运动的影响。 结构观测与准静态力学测试的结果相关。 职业发展计划将这些研究目标与高中，本科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。 这是通过为经济和社会风险高中学生开发一个密集的，信息丰富的和娱乐性的为期两周的暑期课程来实现的。 暑期课程侧重于在体育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。 通过比较当前使用的材料与新材料（大块金属玻璃）的相关性能，学生和教师将对材料选择过程有所了解，并了解材料的基本科学进步如何转化为实用技术。 它将为教师提供现代技术材料的相关实例，演示和实验的有用想法，以及在大学中进一步专业发展的联系人。块体玻璃形成合金的最新发展为金属玻璃的工程应用开辟了新的领域。 金属玻璃现在可用于其独特的机械性能具有优势的应用中。 这些发展突出表明，需要更好地理解金属玻璃永久变形的基本机制 *