Simulations of Shear bands in Metallic Glasses with Mesoscale Modeling

Abstract

Metallic glasses (MGs) have many attractive advantages such as high yield strength, high hardness, high wear resistance, high fracture toughness, and low friction coefficient. However, the localized deformation and poor ductility due to shear bands prohibit the further applications of MGs. The localized deformation could be controlled by the residual stresses in MGs. In this study, a mesoscale model which combines the kinetic Monte Carlo algorithm (kMC) and the finite element method (FEM) is constructed to investigate the effects of residual stresses on deformation behaviors of MGs. The developed computational framework is implemented by integrating in-house Matlab program for kMC and commercial finite element software, Abaqus. In the mesoscale model, a shear transformation zone (STZ) with nanoscale volume is the basic deformation unit and is represented by an element in the FEM model. Each element whether is transformed into an STZ is determined by the kMC algorithm according to its energy state. The developed mesoscale model can simulate the deformation process of MGs with the time and length scales which are greater than those by atomistic modeling. Finally, a sanity check was performed to verify the accuracy of FEM in solving Eshelby’s inclusion problem. Then the developed computational framework is applied to simulate the uniaxial tension test of the metallic glass specimen with different residual stresses. Simulation results demonstrate that the residual stresses could dominate the occurrences of STZs and change the stress–strain curve of MGs.