Predictive Modelling of the Structure and Phase Stability of High-Entropy Materials: Case Study of Al_xCrFeCoNi

Contributed talk at the 2024 MRS Spring Meeting.

Abstract

In the rapidly developing field of high-entropy materials, computational forward modelling approaches are an important tool to help guide experiment towards appropriate compositions. Starting from a given combination of constituent elements, we would like to be able to predict both the crystal structure and propensity to form either an disordered solid-solution or an intermetallic phase, as this will enable us to go on to predict subsequent macroscopic materials properties. We present results from a first-principles-based, all-electron Landau theory which has previously been used with success to study the Cantor alloy and its derivatives [1,2], as well as the refractory high-entropy alloys [3]. We study the Al_xCrFeCoNi system for x between 0 and 2, and demonstrate that our approach successfully reproduces the experimentally observed crystal structure and phase behavour of this material. We successfully predict the A1+B2 coexistence region of the phase diagram, explain the lack of observation of an atomically disordered A2 phase, and give insight into the preferred low-temperature atomic arrangements. As the methodology is first-principled, we are able to explain ordering tendencies in terms of materials’ underlying electronic structure, and pull out qualitative rules to explain ordering tendencies in these complex systems.

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).