Modelling Atomic Arrangements in Multicomponent Alloys: A First-Principles-Based Approach
Date:
Invited speaker at the University of Bristol’s `Quantum Matter’ seminar.
Abstract
Advancing both fundamental understanding and technological application in the rapidly developing field of high-entropy materials, computational-forward modelling approaches are an important tool to help guide experiment. Starting from a given combination of constituent elements, we would like to be able to predict a material’s crystal structure, its thermodynamic stability, as well as the nature of emergent atomic short- and long-range order, as this will enable us to go on to predict subsequent macroscopic materials properties. In addition, it is necessary that modelling approaches be highly computationally efficient; the space of candidate materials is vast and thousands of potential compositions may need to be rapidly screened to search for materials compositions with desirable properties.
In this talk, I will outline a novel approach for modelling atomic arrangements in multicomponent alloys that satisfies the above requirements. A key quantity in this approach an approximate form of the alloy free energy that is evaluated ab initio via density functional theory calculations within the KKR-CPA formalism. A linear response calculation is then applied to this free energy to infer disorder-order transitions directly via a Landau-type theory. In addition, the linear response calculation enables extraction of parameters for a simple, pairwise form of the alloy internal energy suitable for atomistic, Monte Carlo simulations. I will present a summary of results obtained applying the approach to two prototypical families of high-entropy alloys, the Cantor-Wu alloys [1,2] and selected refractory alloys [3]. In addition to outlining how the approach correctly predicts the phase behaviour of these complex systems, I will also outline how the underlying description of a material’s electronic structure enables intuition to be drawn as to the physical origins of ordering. Finally, I will present an outlook on development of the method, including extending the class of systems to which it can be applied, and interfacing it with a variety of techniques for assessing macroscopic materials properties, including the development of machine-learned interatomic potentials.
References
[1] C. D. Woodgate, J. B. Staunton, Phys. Rev. B, 105, 115124 (2022).
[2] C. D. Woodgate, J. B. Staunton, Phys. Rev. Mater. 7, 013801 (2023).
[3] C. D. Woodgate, D. Hedlund, L. H. Lewis, J. B. Staunton, Phys. Rev. Mater. 7, 053801 (2023).