Maximum strength and dislocation patterning in multi-principal element alloys

Abstract

Multi-principal element alloys (MPEAs), commonly termed as medium- or high-entropy alloys containing three or more components in high concentrations, render a tunable chemical short-range order (SRO). Leveraging large-scale atomistic simulations, we probe the limit of Hall-Petch strengthening and deformation mechanisms in a model CrCoNi alloy and unravel chemical short-range ordering effects. It is found that, in the presence of SRO, the maximum strength is appreciably increased, and the strongest grain size drifts to a small value. Additionally, the propensity for faulting and deformation transformation is reduced and accompanied by the intensification of planar slip and strain localization. We reveal strikingly different deformation microstructures and dislocation patterns that prominently depend on crystallographic grain orientation and the number of slip planes activated during deformation. Grain of single planar slip attains the highest volume fraction of deformation-induced structure transformation, and grain with double active slip planes develops the densest dislocation network. These results advancing the fundamental understanding of deformation mechanisms and dislocation patterning in MPEAs suggest a mechanistic strategy for tuning mechanical behavior through simultaneously tailoring grain texture and local chemical order.

References in corpus (5)

• Structure identification methods for atomistic simulations of crystalline materials
• Verification of Short-Range Order and Its Impact on the Properties of the CrCoNi Medium Entropy Alloy
• Tunable stacking fault energies by tailoring local chemical order in CrCoNi medium-entropy alloys
• Strengthening in multi-principal element alloys with local-chemical-order roughened dislocation pathways
• A scalable parallel Monte Carlo algorithm for atomistic simulations of precipitation in alloys

Cited by in corpus (4)

• Nonequilibrium chemical short-range order in metallic alloys
• A simple model for short-range ordering kinetics in multi-principal element alloys
• Dislocation-mediated short-range order evolution during thermomechanical processing
• Benchmarking Chemically Scalable Machine-Learning Interatomic Potentials for Large-Scale Simulations of Multicomponent Alloys