Effect of atomic types and concentration on the mechanical properties of CoNi-based concentrated solid-solution alloys

Concentrated solid-solution alloys (CSAs) are a new type of alloy material with high strength, extreme hardness, remarkable corrosion resistance, and excellent radiation resistance. The mechanical properties of CSAs are strongly determined by the types and concentration of component elements, which provide a large space for design. In this work, molecular dynamics simulations were implemented to investigate the mechanical properties of CoNi-based CSAs. Our study showed that there is a significant effect of constituent types on the yield stress and Young's modulus of CoNi-based CSAs. The yield stress and Young's modulus of CoNiFeAlCu CSAs with equal atomic ratios were found to be 3.02 and 70.94 GPa, respectively. With the increase in the Fe concentration, the yield stress and Young's modulus of the CSAs decrease gradually; on the contrary, these properties increase gradually with an increase in the Al concentration. The CoNiFeCuAl 6 CSA was found to exhibit high strength and good plastic deformation ability, which originates from the significant increase in the dislocation density. Hence, the large design space of CSAs presents a great opportunity to select CSAs with excellent mechanical properties for structural applications.