Fundamental mechanisms of removal of stacking fault tetrahedra by mobile low energy boundaries

技术总结：这项工作的目的是了解通过移动双边界（TBs）积极参与和快速去除堆叠故障四面体（SFTs）的基本机制。最终目标是设计出能够在中低温下有效去除SFTs的先进金属材料。sft是中子或质子辐照的面心立方结构金属材料的有害缺陷，可引起明显的硬化和膨胀。PI将使用原位辐射和原位纳米压痕技术的组合来研究SFTs与TBs的相互作用。这些研究可以解释TBs对SFTs的湮灭，并为验证MD模拟预测的湮灭机制提供重要信息。此外，TBs的显著移动性可能使其成为消除辐射引起的不可移动缺陷（如SFTs）的有吸引力的候选者。非技术总结：如果成功，这项研究的好处将包括发现下一代核反应堆抗膨胀结构材料设计的重要标准，并为进一步探索辐射诱导双边界迁移的物理基础。该项目将为德克萨斯农工大学（TAMU）的研究生和本科生提供研究培训。通过TAMU资助的“博士之路”计划，将特别努力招收女性和其他少数民族学生。该项目还将通过在介绍先进纳米材料时将相关成果纳入课堂，加强材料科学和纳米工程课程，并使新成立的材料科学与工程系受益。PI将通过NSF-RET计划让高中教师参与研究项目，并参加国际会议，向更广泛的受众传播结果。与麦克马斯特大学和几个能源部国家实验室的合作将为研究生提供夏季研究经验。

TECHNICAL SUMMARY: The objective of this work is to understand the fundamental mechanisms through which mobile twin boundaries (TBs) actively engage and rapidly remove stacking fault tetrahedra (SFTs). The ultimate goal is to design advanced metallic materials that can effectively remove SFTs at low-to-intermediate temperatures. SFTs are detrimental defects in neutron or proton irradiated structural metallic materials with face-centered-cubic structures as they can induce significant hardening and swelling. The PI will use a combination of in situ radiation and in situ nanoindentation technique to investigate the interaction of SFTs with TBs. These studies can explain the annihilation of SFTs by TBs and provide crucial information to validate annihilation mechanisms predicted by MD simulations. Also significant mobility of TBs may make them attractive candidates to remove radiation induced immobile defects, such as SFTs. NON-TECHNICAL SUMMARY:If successful, the benefits of this research will include discovery of important criteria for the design of swelling resistant structural materials for next generation nuclear reactors, and offer the basis for further exploration of physics of radiation induced twin boundary migrations. This project will provide research training to graduate and undergraduate students at Texas A&M University (TAMU). Special effort will be made to recruit female and other minority students through the "Pathway to Ph.D program" funded by TAMU. The project will also enhance the materials science and nanoengineering curricula by incorporating relevant results into classes when introducing advanced nanomaterials, and benefit the new formed Department of Materials Science and Engineering. The PI will disseminate results to a much broader audience by involving high school teachers in the research project through NSF-RET program, and attending international conferences. Collaborations with McMaster University and several DOE National Laboratories will offer graduate students summer research experience.