Structural evolution and dislocation behaviour study during nanoindentation of Mo₂₀W₂₀Co₂₀Ta₂₀Zr₂₀ high entropy alloy coated Ni single crystal using molecular dynamic simulation

ABSTRACT

In this present study, deformation behaviour of Mo₂₀W₂₀Co₂₀Ta₂₀Zr₂₀ high entropy alloy (HEA) coated single crystal (SC) nickel (Ni) subjected to nanoindentation test have been investigated to study the mechanical properties and underlying mechanism during nanoindentation test using molecular dynamics (MD) simulation with embedded atom method (EAM) potential. Centro-Symmetry Parameter (CSP) Analysis and Radial Distribution Function (RDF) plots are obtained to get insight of structural evolution during nanoindentation and thereby determine the underlying physics of deformation. During nanoindention test Stacking faults (SFs) formation, dislocation generation, dislocation loops, Lomer–Cottrell (LC) lock and Hirth lock formation due to dislocation-dislocation interaction are observed. At higher indentation depth, formation of dislocation loops is augmented, which indicates nanoindentation deformation is found to be Stacking Fault dominated deformation. The accumulation and relaxation of shear stress near indenter tip at the time of deformation process under nanoindentation test causes the variation of dislocation density, strain hardening, and plastic deformation, which is influenced by the formation of dislocation barriers (LC and Hirth locks) and dislocation loops (shear and prismatic loops).

KEYWORDS:

• High entropy alloy
• molecular dynamics simulation
• dislocation
• stacking fault
• dislocation loop

Acknowledgments

The authors want to thank the computer centre of National Institute of Technology Rourkela for providing high-performance computing facility (HPCF) required for performing this study.

Disclosure statement

No potential conflict of interest was reported by the authors.