Enhanced lattice distortion, yield strength, critical resolved shear stress, and improving mechanical properties of transition-metals doped CrCoNi medium entropy alloy

Abstract

The effect of transition-metals (TM) addition on the mechanical properties of CrCoNi medium entropy alloys (MEAs) was investigated. Molecular dynamics (MD) simulations were carried out to evaluate the atomic distortion and yield strength and critical resolved shear stress (CRSS) quantitively. The MD simulation results indicate that the lattice distortion and yield strength agree with the other experimental results. The addition of 4 atomic% of transition metals enhances the lattice distortion and yield strength of the CrCoNi alloy by ∼30% and retains high ductility and strengthening ability. Also, the elastic moduli, anisotropy factor, Pugh's ratio, and the hardness were investigated. Furthermore, we performed MD simulations to obtain the CRSS and the root-mean-square-atomic-displacement (RMSAD) of equiatomic and near-equiatomic CrCoNi MEAs. We demonstrated that an approximately linear relationship exists between the RMSAD and the CRSS for these alloying systems. A more realistic embedded atom method (EAM) potential also verified the universality. These simulation results will be useful in the future development and research of CrCoNi-based quaternary alloys with improved mechanical properties.