DFT-Based Analysis on Structural, Electronic and Mechanical Properties of NiCoCr Medium-Entropy Alloy with C/N/O

TL;DR

This paper uses computational methods to study how adding C, N, and O affects the strength and ductility of NiCoCr alloys.

Contribution

The study reveals how interstitial elements influence mechanical properties and stacking fault energy in NiCoCr medium-entropy alloys.

Findings

C, N, and O occupy octahedral interstitial sites, reducing stress and enhancing strength and deformability.

Doping with C, N, and O increases stacking fault energy, improving mechanical properties.

Electronic interactions are strengthened, hindering dislocation glide and increasing hardness.

Abstract

This study employs first-principles calculations combined with the Special Quasirandom Structure (SQS) technique to investigate the impact of three interstitial elements C, N, and O, on the mechanical properties and stacking fault energy (SFE) of NiCoCr medium-entropy alloys. The results indicate that non-metallic O, C, and N tend to occupy octahedral interstitial sites, which can effectively release stress concentration and enhance the strength and deformability of the material. Differential charge density analysis shows that the dissolution of C, N, and O significantly alters the surrounding electronic environment, strengthening the interaction between solute atoms and metal atoms, thereby hindering dislocation glide and increasing the strength and hardness of the material. Elastic property analysis indicates that NiCoCr alloys doped with C, N, and O exhibit good ductility and anisotropic characteristics. Furthermore, the study of stacking fault energy reveals that the doping with C, N, and O can significantly increase the stacking fault energy of NiCoCr alloys, thereby optimizing their mechanical properties. These findings provide theoretical evidence for the design of advanced high-entropy alloys that combine high strength with good ductility.

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