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

A Jarlöv and WM Ji and R Babicheva and YJ Tian and ZH Hu and HL Seet and LM Tan and F Liu and Y Liu and MLS Nai and U Ramamurty and K Zhou, MATERIALS & DESIGN, 240, 112840 (2024).

DOI: 10.1016/j.matdes.2024.112840

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.

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