Tailoring short-range order and dislocation evolution in Cr-Co-Ni medium-entropy alloys: A molecular dynamics study

The research community has recently been captivated by the atomic-scale short-range order observed in highand medium-entropy alloys. However, significant challenges persist in improving the mechanical performance through manipulation of the short-range order. Herein, molecular dynamics simulations are employed to establish the correlation between this ordering and the chemical composition for the Cr-Co-Ni medium-entropy alloys. It is demonstrated that atomic-scale clustering can be tailored through adjusting the chemical composition. Particularly, it can be promoted by decreasing the content of elements that do not participate in the clusters. The short-range ordering plays a significant role in affecting the dislocation evolution and tensile properties. Reducing the tendency to form Cr-Co clusters yields enhanced strengthening due to the increased local unstable stacking fault energy. Increasing the tendency to form Ni-Ni clusters instead results in enhanced strain hardening due to the high sessile dislocation density impeding the movement of dislocations. These findings unveil the crucial role of chemical composition on short-range ordering and have significant implications on the design of high-performance high- and medium-entropy alloys.