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

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. Here 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 0 ≤ x ≤ 2 and demonstrate successful reproduction of 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.<br/><br/><b>Acknowledgements</b><br/>We gratefully acknowledge the support of the UK EPSRC, Grant No. EP/W021331/1. C.D.W. is supported by a studentship within the UK EPSRC-supported Centre for Doctoral Training in Modelling of Heterogeneous Systems, Grant No. EP/S022848/1. This work was also supported in part by the U.S. Department of Energy, Office of Basic Energy Sciences under Award Number DE SC0022168 (for atomistic insight) and by the U.S. National Science Foundation under Award ID 2118164 (for advanced manufacturing aspects).<br/><br/><b>References</b><br/>[1] C. D. Woodgate and J. B. Staunton, Phys. Rev. B <b>105</b>, 115124 (2022).<br/>[2] C. D. Woodgate and J. B. Staunton, Phys. Rev. Mater. <b>7</b> 013801 (2023).<br/>[3] C. D. Woodgate D. Hedlund, L. H. Lewis, J. B. Staunton, Phys. Rev. Mater. <b>7 </b>053801 (2023).