Short-Range Order in High-Entropy Superalloys—First Principles Theory and Atomistic Modelling

Short-Range order (SRO) can be either beneficial or detrimental to the properties of novel superalloys. An understanding of phase behaviour and underlying physical mechanisms driving ordering is therefore essential. We present results from an all-electron, first principles, Landau-type theory which enables us to obtain SRO directly, and also to obtain parameters suitable for atomistic modelling to understand incipient order in these materials. Following successful earlier work on the Ni-based superalloys[1], I will present new results on the refractory-based superalloys, which are being studied as candidate materials for components in fusion reactors, due to their exceptional strength, high melting points, and high levels of resistance to radiation. We present a complete description of SRO in the five-component VNbMoTaW and its derivatives. Further, we elucidate the origins of this order and describe the underlying physical mechanisms by which it is driven.<br/><br/>1. C. D. Woodgate, J. B. Staunton, "Compositional Phase Stability in medium-entropy and high-entropy Cantor-Wu alloys from an ab initio all-electron Laundau-type theory and atomistic modelling", Phys. Rev. B, <b>105</b> 115124 (2022).