Grain Stability in Nanostructured Metals

纳米结构金属中的晶粒稳定性本项目主要研究金属中超细和纳米结构晶粒的稳定性，包括面心立方和六方密排晶体结构，以及含有纳米晶粒或纳米孪晶的金属。 纳米孪生铜和纳米粒度钛将使用多种方法进行研究，包括微压痕、动态变形和微拉伸测试。钛中的动态变形专门设计用于记录钛晶界迁移导致超细晶粒结构不稳定的趋势。互补的理论研究将包括使用我们新开发的有限温度准连续方法的原子模拟。在这些研究中，将模拟纳米尺寸的孪晶结构的变形，以探索位错与孪晶的相互作用以及孪晶边界的潜在运动（即不稳定性）。教育活动包括从代表性不足的群体中选出的研究生和本科生的培训，其中两名本科生已经在从事直接相关的课题。建立了一个网站，以迅速传播新的结果，并作为其他人添加新获得数据的资料库。我们参加了一个叫？《通向未来的桥梁》圣地亚哥的一个项目，旨在将代表性不足的少数民族的职业生涯转变为科学。我们还参加了加州数学和科学暑期学校（COSMOS），旨在为9 - 12年级的学生谁表现出对数学和科学的兴趣。我们在这方面的重点将是纳米技术。

Grain Stability in Nanostructured MetalsAbstractThis project is concerned with fundamental studies of the stability of ultra-fine and nanstructured grains in metals, both with face centered cubic and hexagonal close packed crystal structures, and in metals that contain either, or both, nano-sized grains or nano-sized twins. Nano-twinned copper and nano-grain size titanium will be studied using a variety of methods, including micro-indentation, dynamic deformation, and micro-tensile testing. The dynamic deformation in titanium is designed specifically to document the tendency of titanium grain boundaries to migrate leading to instability of the ultra-fine grain structure. Complimentary theoretical studies will include atomistic simulation using our newly developed finite temperature quasi-continuum method. In these studies simulations of the deformation of nano-sized twinned structures will be performed to explore the interaction of dislocations with twins and the potential motion (that is the instability) of twin boundaries.Educational activities include the training of graduate students and undergraduate students chosen from under represented groups; two such undergraduate students are already working on directly related topics. A web site is established to rapidly disseminate novel results and to act as a repository for others to add newly obtained data. We are participating in a program called ?Bridges to the Future?, a San Diego program designed to transition the careers of under represented minorities into science. We also participate in the California State Summer School for Mathematics and Science (COSMOS) aimed at 9th-12th graders who demonstrate interest in math and science. Our focus in this will be nanotechnology.