Competing Grain-Interior and Grain-Boundary Deformation Mechanisms in Nanocrystalline Materials and Thin Films

纳米晶材料和薄膜中晶粒内部和晶粒边界变形机制的竞争PI：Huajian Gao，Brown University摘要本提案的目的是研究具有晶粒边界和晶粒内部变形机制之间强耦合的纳米晶材料和薄膜的机械性能。本研究将采用理论分析与数值计算相结合的方法（积分微分方程模型、基于有限元的介观模型、离散位错动力学和分子动力学方法）。将对一些基本问题进行系统的研究，包括晶粒尺寸/膜厚度为100 nm或更小的系统中晶界和晶粒内部的竞争变形，纳米晶材料和纳米晶膜中异质晶界扩散率和滑动阻力的影响，晶界扩散和晶界滑动之间的相互作用以适应相容变形，该项目将产生新的知识和基本的理解，可以为现代技术中的广泛应用提供见解和指导，包括微电子和光电子学中的薄膜结构，MEMS器件，燃气轮机中的热障涂层，摩擦涂层和材料工程纳米技术。该项目的教育组成部分包括博士生的培训，本科生的指导，以及将最先进的研究成果融入布朗大学现有的研究生和本科生工程课程，目前学生对纳米材料和结构的界面力学有浓厚的兴趣。额外的外联活动将由布朗调解？该奖项是由美国材料研究院材料结构与金属工程研究中心（CMMI - Mechanics Structure of Materials and DMR-Metals programs）共同资助的，该中心建立了一套优秀的外展教育项目。

Competing Grain-Interior and Grain-Boundary Deformation Mechanisms in Nanocrystalline Materials and Thin FilmsPI: Huajian Gao, Brown UniversityAbstract The objective of this proposal is to investigate mechanical properties of nanocrystalline materials and thin films with strong coupling between grain boundary and grain interior deformation mechanisms. A combination of theoretical analysis and numerical techniques (integro-differential equation modeling, finite element based mesoscopic modeling, discrete dislocation dynamics and molecular dynamics methods) will be adopted in the study. A systematic investigation will be conducted on a number of fundamental issues including competing deformation in grain boundaries and grain-interiors in systems with grain sizes/film thicknesses on the order of 100 nm or smaller, effects of heterogeneous grain boundary diffusivity and sliding resistance in nanocrystalline materials and ultrathin films, interplay between grain boundary diffusion and grain boundary sliding to accommodate compatible deformation, and mechanical behaviors of thin films with surface and grain boundary diffusion.This project will generate new knowledge and fundamental understanding that may provide insights and guidelines for a wide range of applications in modern technologies including thin film structures in microelectronics and optoelectronics, MEMS devices, thermal barrier coatings in gas turbines, tribological coatings and nanotechnology of materials engineering. The educational components of the project include training of a PhD student, mentoring of undergraduates, and assimilation of state-of-the-art research results into the existing graduate and undergraduate courses in engineering at Brown where there are currently strong student interests in interfacial mechanics of nanoscale materials and structures. Additional outreach activities will be mediated by Brown?s Materials Research Science and Engineering Center (MRSEC) which has established a set of excellent outreach educational programs.This award is co-funded by CMMI - Mechanics & Structure of Materials and DMR-Metals programs.