Modeling of trans-grain twin transmission in AZ31 via a neighborhood-based viscoplastic self-consistent model

Abstract

The impact of twin transmission between neighboring grains as a contributor to overall twin activity is considered via a neighborhood viscoplastic self-consistent (NVPSC) model. The NVPSC model is an extension of a stochastic model for twin nucleation developed by Niezgoda et al. and a dislocation density based hardening law model developed by Knezevic et al. Beyond the baseline combined framework, the new model tracks sets of neighboring grains and allows twin transmission between them under certain conditions. The influence of grain boundary (GB) character is included in the stochastic models of twin nucleation and transmission. The starting texture from a rolled magnesium alloy AZ31B sheet was obtained using electron backscatter diffraction (EBSD) for initial input into the NVPSC. The sample was further deformed by uniaxial compression to encourage twin formation and the corresponding texture information was collected using EBSD. The accuracy of simulated twin activity was determined by comparing it with the twin activity seen in the deformed sample. The total number of predicted twins and the number of transmission twins is found to agree favorably with those observed via the EBSD scans. This validation demonstrates the significance of incorporating twin transmission as a twin formation mode in predictive models for this material.