Atomistic simulation of short-range ordering on the mechanical behavior and deformation mechanism of amorphous high-entropy alloys

Short-range ordering (SRO) is an important characteristic of high-entropy alloys (HEAs), which has a significant impact on their mechanical properties and deformation behavior. However, the study of SRO structure on amorphous HEAs is still in its very early stages. Here, the effect of SRO structure on the mechanical properties and plastic deformation behavior of amorphous CoCrFeMnNi HEAs is systematically investigated by a hybrid molecular dynamics/Monte Carlo simulation method. The results indicate that as the degree of SRO increases, the yield stress of the amorphous HEAs gradually rises. Concurrently, the plastic deformation mechanism of the alloys undergoes a transition from homogeneous plastic deformation to one dominated by shear bands. To be specific, a moderate level of SRO not only bolsters strength but also preserves substantial plasticity. The results also show that although the yield stress of both models with and without SRO structures decreases with increasing temperature, the former has distinct "soft" and "hard" zone structures, which effectively suppress atomic thermal motion and maintain relatively high values even under high temperature conditions. Further analysis indicates that the SRO structures promote the formation of dense clusters, which enhances the stiffness of the alloys, but suppresses the dispersion distribution of shear transform zone. This study provides a theoretical basis for the microstructure design of amorphous HEAs based on SRO modulation.