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

Abstract

The research community has recently been captivated by the atomic-scale short-range order observed in high- and 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.

Keywords

• Medium-entropy alloys
• Molecular dynamics simulations
• Short-range order
• Energy landscape
• Dislocation evolution