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

Brown University, Providence RI

Investigators

Abstract

Competing Grain-Interior and Grain-Boundary Deformation Mechanisms in Nanocrystalline Materials and Thin Films PI: Huajian Gao, Brown University Abstract 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.