Molecular Dynamics Studies on the Prediction of Interface Strength of Cu (metal)-CuZr (metallic glass) Metal Matrix Composites

Abstract

The aim of this investigation is to predict the interface strength of metal (Cu-matrix)–metallic glass (Cu50Zr50-reinforcement) composites via molecular dynamics (MD) simulations. Simulation box size of 100 Å (x) × 110 Å (y) × 50 Å (z) is used for the investigation. At first Cu–Cu50Zr50 crystalline model is constructed with the bottom layer (Cu) of 50 Å and the top layer of 60 Å (Cu50Zr50) in height along y–direction. Thereafter, Cu50Zr50 metallic glass is obtained by rapid cooling at a cooling rate of 4 × 1012 s-1. The interface model is then equilibrated at 300 K for 500 ps to relieve the stresses. EAM (Embedded Atom Method) potential is used for modelling the interaction between Cu–Cu and Cu–Zr atoms. The fracture strength of Cu–Cu50Zr50 model interface is determined by tensile (mode–I) and shear (mode–II) loading. Periodic boundary conditions are applied along z–direction for shear while along x– and z–directions for tensile tests. A timestep of 0.002 ps is used for all the simulations. Tensile and shear tests are carried out at varying strain rates (108 s-1, 109 s-1 and 1010 s-1) and temperatures (100K and 300 K). The interface model is allowed for full separation under both the deformation modes. It is found that tensile as well as shear strength decrease with increase in temperature and increase with strain rate, as expected. Further, the maximum stress in shear is smaller than that in tensile at all strain rates and temperatures. Critical observations of the obtained results on Cu–Cu50Zr50 composites indicate better shear strengths as compared to the results of metal (matrix)-ceramic (reinforcement) composites available in the literature. Hence it can be concluded that metallic glass acts as a better reinforcement material than the popular ceramic reinforcements.