Multi-scale simulations of the mechanical behaviors of the W-Cu joint interface with a diffusion layer

Abstract

Abstract At the interface of W-Cu after direct jointing, diffusion layers with a thickness of approximately 22 nm are present but often overlooked in simulations of mechanical properties. This study establish an interface model with a W-Cu diffusion layer using molecular dynamics (MD). The influence of the diffusion layer on the elastic-plastic behaviors, dissipation mechanisms and fracture properties of the interface is analyzed under mode-I (perpendicular to the interface) and mode-II (parallel to the interface). The results demonstrate that the interface model with a diffusion layer exhibits superior mechanical properties under mode-I and mode-II loading when compared to the model without a diffusion layer. Furthermore, a multi-scale method based on the classical Paris law is then proposed, which combines molecular dynamics (MD) and finite element methods to investigate the fatigue crack propagation of W-Cu bimetallic composites under cyclic loading and predict their fatigue life. The findings of this study are meaningful for improving the mechanical properties of W-Cu interface materials, predicting the material's lifespan, and guiding related engineering applications.