Structure, short-range order, and phase stability of the AlxCrFeCoNi high-entropy alloy: insights from a perturbative, DFT-based analysis

• Published in: npj computational materials 2024-11, Vol.10 (1), p.271
• Main Authors: Woodgate, Christopher D., Marchant, George A., Pártay, Livia B., Staunton, Julie B.
• Format: Article
• Language: English
• Subjects: 639/301/1023/1026; 639/301/1034/1038; 639/301/119/1002; 639/766/119; 639/766/25; Algorithms; Alloys; Approximation; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coherent potential approximation; Computational Intelligence; Density functional theory; Energy; Entropy; High entropy alloys; Internal energy; Iron; Low concentrations; Materials Science; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Melt temperature; Nickel aluminides; Nickel base alloys; Nickel compounds; Phase stability; Physics; Potential energy; Short range order; Solid solutions; Temperature; Theoretical
• ISSN: 2057-3960
• DOI: 10.1038/s41524-024-01445-w

We study the phase behaviour of the Al x CrFeCoNi high-entropy alloy. Our approach is based on a perturbative analysis of the internal energy of the paramagnetic solid solution as evaluated within the Korringa-Kohn-Rostoker formulation of density functional theory, using the coherent potential approximation to average over disorder. Via application of a Landau-type linear response theory, we infer preferential chemical orderings directly. In addition, we recover a pairwise form of the alloy internal energy suitable for study via atomistic simulations, which in this work are performed using the nested sampling algorithm, which is well-suited for studying complex potential energy surfaces. When the underlying lattice is fcc, at low concentrations of Al, depending on the value of x , we predict either an L1 2 or D0 22 ordering emerging below approximately 1000 K. On the other hand, when the underlying lattice is bcc, consistent with experimental observations, we predict B2 ordering temperatures higher than the melting temperature of the alloy, confirming that this ordered phase forms directly from the melt. For both fcc and bcc systems, chemical orderings are dominated by Al moving to one sublattice, Ni and Co the other, while Cr and Fe remain comparatively disordered. On the bcc lattice, our atomistic modelling suggests eventual decomposition into B2 NiAl and Cr-rich phases. These results shed light on the fundamental physical origins of atomic ordering tendencies in these intriguing materials.