A micromechanics-based incremental damage theory of bulk metallic glass matrix composites

Abstract

Based on the Mori–Tanaka’s mean field concept, a micromechanics-based incremental damage theory was developed to investigate the mechanical performance of bulk metallic glass matrix composites under tension. Firstly, the shear band was considered to be a microcrack, and therefore a spherical fictitious inclusion-containing microcracks and the surrounding bulk metallic glass matrix were constructed. Based on the equivalence between the effective elasticity of microcrack-containing media and porous material, the volume fraction of the fictitious inclusion could be determined by the density of microcracks generated during a strain increment. The stress-based Weibull probability distribution function and percolation theory were applied to describe the microcrack evolution that results in the progressive damaging of bulk metallic glass composites. Based on the present model, the impact of shear bands on the tensile ductility was discussed for the composites with various microstructures. The predictions are in fairly good agreement with the experimental data, demonstrating that the developed analytical model is capable of successfully capturing the main features, such as yield strength, strain hardening, and stress softening elongation, of particle-toughened bulk metallic glass. The main conclusions will shed some light on optimizing the microstructures in effectively improving the tensile ductility of bulk metallic glass composites.