SLIP, TWINS AND VOIDS: TRIAXIALITY EFFECTS IN MAGNESIUM

Abstract

The complex deformation processes and high plastic anisotropy of magnesium (Mg) and its alloys are often referred to as the origins of poor ductility under general loading conditions. Understanding the anisotropy-stress state-microstructure interaction is imperative for strategies to enhance fracture resistance of Mg alloys. In this work, three-dimensional crystal plasticity based finite element calculations are used to assess plastic deformation and damage evolution under three-dimensional stress state. The first part of thesis discusses the independent effect of inherent plastic anisotropy, stress state and texture in determining the micromechanics of deformation. The second part focuses on the independent roles of crystal orientation and stress state on damage evolution by void growth in single crystal Mg. Micromechanical analysis of void growth process brings forth the interplay between stress state and deformation mechanisms in determining the void growth behavior. The results are key to developing improved homogenization-based ductile damage models.