Effects of stacking fault energy on the deformation behavior of CoNiCrFeMn high-entropy alloys: A molecular dynamics study

Tailoring stacking fault energy (SFE) is an effective way for enhancing mechanical properties of certain high entropy alloys (HEAs) such as the prototype Cantor alloy. However, the underlying mechanism, especially the atomistic origins for the enhanced plasticity and strength, is still unclear. In this work, we performed molecular dynamics simulations to investigate the mechanical behavior of CoxNi40-xCr20Fe20Mn20 (x = 10, 20, and 30 at. %) HEAs under tensile loading. The results show that the SFE decreases with the increase in Co concentration and favors the formation of continuous stacking fault networks on which multiple plastic deformation carriers including stacking faults, dislocations, twins, and martensitic transformation were sequentially activated. The activation and complex interaction of these multiple carriers mainly contribute to the improved plasticity, and the increased stair-rod dislocations result in the enhanced strength in Co30Ni10Cr20Fe20Mn20 HEA. The current findings may be important for the understanding of SFE effects at the atomistic scale and also shed light on designing of high-performance HEAs.

Automated summary

The study found that the stacking fault energy (SFE) of high entropy alloys decreases with an increase in Co concentration, favoring the formation of continuous stacking fault networks. The activation and complex interaction of multiple plastic deformation carriers are the main contributors to improved plasticity. Additionally, the increased presence of stair-rod dislocations in Co30Ni10Cr20Fe20Mn20 HEA results in enhanced strength.