Plastic deformation mechanism in crystal-glass high entropy alloy composites studied via molecular dynamics simulations

Recent experimental observations have demonstrated the possibility to develop a crystal-glass composite (CGC) with high strength and ductility by incorporating dual-phase of high entropy alloys (HEAs) and metallic glasses (MGs). In the current work, molecular dynamics simulations were performed to uncover the plastic deformation mechanism in CGC structures consisting of the CoCrFeMnNi HEA and its MG counterpart. A fully crystalline polycrystal model and two CGC models were simulated to reveal the influence of the MG phase thickness and the temperature on the plastic deformation behaviors. It is found that the MG phase can effectively inhibit deformations mediated by grain boundary and dislocations emitted from the glass-crystalline interface, which enhances the yielding stress and strain in the CGC model. At the low temperature (T ≤ 300 K) regime during which the MG phase deform via the shear transformation zone, the thinner MG phase was more effective in strengthening due to the more limited space for shear band formation compared with the thicker MG phase. At the high temperature (T ≥ 700 K) regime that the MG phase mainly deform by homogeneous viscous flow, the MG phase acts as a softer phase, which can contribute to good deformability and thermal stability of the nanograined crystalline phase. The current work may shed light on an in-depth understanding of the deformation mechanisms of the CGCs and may advance the development of metallic materials with a synergy of high strength and ductility.