Atomic short-range order in high-entropy alloys: Concentration waves in the multicomponent setting
Date:
Invited talk at the 2025 American Physical Society (APS) Global Physics Summit (March Meeting).
Abstract
High-entropy alloys represent a challenging class of system to model on account of the huge range of potential chemical compositions and vast space of possible atomic configurations. Such multicomponent alloys do not always form disordered solid solutions—depending on the precise composition there is often a degree of chemical short-range order present, and sometimes intermetallic phases are seen to emerge. It is desirable that computational and theoretical tools be developed to model the thermodynamics and phase stability of these systems, to interpret existing data and guide experiment toward new compositions with improved physical properties. Here, we describe the implementation and analysis of a first-principles theory for the leading terms in an expansion of a Gibbs free energy of a multicomponent alloy in terms of order parameters characterising potential chemical orderings, which we refer to as “concentration waves”. As well as rigorous description of emergent short-range order in the solid solution, the theory allows us to infer the temperature at which a long-range ordered intermetallic phase is expected to emerge, and also to recover a pairwise form of the alloy internal energy (i.e. pair potential) suitable for lattice-based atomistic modelling, facilitating further exploration of the phase space. We present results for a number of prototypical high-entropy alloys, including the Cantor alloy, CrMnFeCoNi, and its derivatives, the refractory high-entropy alloys, and the AlxCrFeCoNi system. The computational cost-effectiveness of the method makes it a good candidate for further exploration in the space of multicomponent alloys, as well as for providing representative atomic configurations for use with other modelling approaches, such as in the development of training datasets for machine-learned interatomic potentials.
Funding Acknowledgments
C.D.W. acknowledges support from an UK Engineering and Physical Sciences Research Council (EPSRC) Doctoral Prize Fellowship awarded by the University of Bristol, and from a studentship within the UK EPSRC-supported Centre for Doctoral Training in Modelling of Heterogeneous Systems, Grant No. EP/S022848/1. C.D.W. and J.B.S. acknowledge support from the UK EPSRC, Grant Nos. EP/T000163/1 and EP/M028941/1.