Abstract
Concentrated solid solutions including the class of high entropy alloys (HEAs) have attracted enormous attention recently. Among these alloys a recently developed face-centered cubic (fcc) equiatomic VCoNi alloy revealed extraordinary high yield strength, exceeding previous high-strength fcc CrCoNi and FeCoNiCrMn alloys. Significant lattice distortions had been reported in the VCoNi solid solution. There is, however, a lack of knowledge about potential short-range order (SRO) and its implications for most of these alloys. We performed first-principles calculations and Monte Carlo simulations to compute the degree of SRO for fcc VCoNi, namely, by utilizing the coherent-potential approximation in combination with the generalized perturbation method as well as the supercell method in combination with recently developed machine-learned potentials. We analyze the chemical SRO parameters as well as the impact on other properties such as relaxation energies and lattice distortions.
Highlights
Multicomponent alloys, known as high entropy alloys (HEAs) or chemically complex alloys (CCAs), have attracted enormous attention in the last decade, from theory and experiment, due to their remarkable materials properties and overwhelming compositional phase space for alloy design [1,2,3]
A goal of the present work is to investigate the degree of short-range order in VCoNi alloy as well as the interplay with lattice distortions and relaxation effects, which is closely related to the exceptional strengthening of the VCoNi alloy [4]
We trained an ensemble of 10 low-rank potential (LRP), which were used in the Monte Carlo (MC) simulations for systems with 108 atoms
Summary
Multicomponent alloys, known as high entropy alloys (HEAs) or chemically complex alloys (CCAs), have attracted enormous attention in the last decade, from theory and experiment, due to their remarkable materials properties and overwhelming compositional phase space for alloy design [1,2,3]. An important issue to address is whether the solid solutions involve local chemical ordering or short-range order (SRO), which could affect, e.g., defect properties and their mechanical properties This has, for example, been demonstrated in recent simulations of computed stacking-fault energies in fcc CrCoNi [6,7]. A number of such techniques are available to address phase stability and, in particular, SRO; among them the coherent-potential approximation (CPA) [17,18] based methods such as the generalized perturbation method (GPM) [19,20,21] in combination with Monte Carlo (MC) simulations or the concentration wave method [22,23] These methods have been extensively employed in the past few years for multicomponent alloys [10,23,24,25,26,27] due to their. E.g., on lattice distortions and solid-solution strengthening contributions, are discussed
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