Collaborative Research: deformation mechanisms of fcc and hcp Cobalt with high-density stacking faults

合作研究：具有高密度堆垛层错的fcc和hcp钴的变形机制

• 批准号: 1642759
• 负责人: Xinghang Zhang
• 金额: $ 24.87万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1642759&HistoricalAwards=false
• 关键词: Collaborative; Research; deformation; mechanisms; fcc

Nontechnical summary:Cobalt (Co), in the form of thin films, is a critical magnetic material with widespread applications in magnetic data storage devices, microelectromechanical and nanoelectromechanical systems (MEMS/NEMS), as well as environmentally benign wear and corrosion resistant coatings. Yet, the mechanical properties of Co films, either in face-centered-cubic (fcc) or hexagonal-close-packed (hcp) form are poorly understood. The principal investigator's recent studies show that high-density stacking faults (SFs) - atomic planes that disrupt the ordered arrangement of atoms - can be introduced into fcc and hcp Co. These SFs may drastically enhance mechanical properties leading to higher strength and ductility of Co. The aim of the project is to elucidate the effect of the density of SFs and systematically investigate the mechanical properties of Co with SFs. The investigators have existing collaborations and their expertise nicely complements each other. The collaboration provides students with the opportunity to gain complementary knowledge in experiments and simulations through mutual visits, lectures and seminars at the participating institutions. The investigators also have arrangement for graduate students to visit the Department of Energy - Center for Integrated Nanotechnologies to access advanced microscopy facilities. The knowledge derived from this project can be incorporated into curricula at both institutions. The co-investigator can leverage successful outreach programs at University of Houston to broaden participation in engineering. The principal investigator can recruit a minority graduate student through the "Pathway to Doctoral Program" from minority institutions. Both investigators continuously supervise undergraduate students and encourage their students to attend major conferences. Technical summary:The objective of this project is to investigate the deformation mechanisms in fcc and hcp Co with high-density SFs. The ultimate goal is to understand the significance of SFs in governing the mechanical properties of metals, and improving the strength and deformability of Co. The investigators combine experiments and molecular dynamics simulations to perform the following major tasks: (1) understand the nucleation of SFs and the formation of intercepted SFs in fcc Co, and tailor the density of SFs in fcc and hcp Co; 2) examine the deformation mechanisms in fcc Co, including dislocation-SF interactions, size effect and work hardening, via a combination of in situ nanoindentation and atomistic modeling; and 3) investigate the deformation mechanisms in hcp Co with high density SFs and understand nucleation mechanisms of deformation twins in hcp Co. This project could reveal the significant role of SFs in mechanical behavior of metals. Furthermore, the combination of novel nanomechanical testing tools with molecular dynamics simulations fills in the knowledge gap through comprehensive interrogation of the deformation mechanisms in fcc and hcp Co with SFs at the atomistic level.

非技术摘要：以薄膜的形式使用钴（CO）是一种临界磁性材料，在磁性数据存储设备，微电机电和纳米机电系统（MEM/NEMS）中具有广泛应用，以及环境良性的磨损和耐腐蚀的耐涂层。然而，以面部为中心的立方体（FCC）或六角形粘膜包装（HCP）形式的CO膜的机械性能知之甚少。 The principal investigator's recent studies show that high-density stacking faults (SFs) - atomic planes that disrupt the ordered arrangement of atoms - can be introduced into fcc and hcp Co. These SFs may drastically enhance mechanical properties leading to higher strength and ductility of Co. The aim of the project is to elucidate the effect of the density of SFs and systematically investigate the mechanical properties of Co with SFs.研究人员进行了现有的合作，其专业知识很好地相互补充。该合作为学生提供了通过参与机构的相互访问，讲座和研讨会在实验和模拟中获得互补知识的机会。研究人员还安排了研究生访问能源部 - 纳米技术中心，以获取高级显微镜设施。可以将来自该项目得出的知识纳入两个机构的课程中。共同投资者可以利用休斯顿大学成功的外展计划来扩大对工程的参与。首席研究人员可以通过少数族裔机构的“博士学位途径”招募少数族裔研究生。两位调查人员都不断监督本科生，并鼓励学生参加主要会议。 技术摘要：该项目的目的是研究具有高密度SFS的FCC和HCP CO中的变形机制。 The ultimate goal is to understand the significance of SFs in governing the mechanical properties of metals, and improving the strength and deformability of Co. The investigators combine experiments and molecular dynamics simulations to perform the following major tasks: (1) understand the nucleation of SFs and the formation of intercepted SFs in fcc Co, and tailor the density of SFs in fcc and hcp Co; 2）检查FCC CO中的变形机制，包括脱位 - SF相互作用，尺寸效应和工作硬化，通过原位纳米指标和原子建模的结合； 3）研究HCP SFS高密度的HCP CO中的变形机制，并了解HCP CO中变形双胞胎的成核机制。该项目可以揭示SFS在金属机械行为中的重要作用。此外，新型纳米力学测试工具与分子动力学模拟的组合通过对FCC和HCP CO中的变形机制与SFS在原子级别上的变形机制的全面询问来填补知识差距。