Body-centered-cubic (BCC) high entropy alloys show exceptional strengths up to 1900K [1]. Fundamental understanding of the mechanisms that control strengthening is necessary to formulate a theory that enables screening over the immense compositional HEA space [2].

Supported by the recent experimental findings in NbTaTiV and CrMoNbV alloys [3], we show with theory [4] that edge dislocations can control the yield strength in BCC high entropy alloys [3]. The theory of edge dislocation strengthening is based on the interaction of the edge dislocations with the random field of solutes in the HEAs. The theory rationalizes and captures a broad range of experiments on BCC alloys.

The theory is cast in an analytical form that is parameter-free and depends on physical quantities (alloy concentrations, lattice parameter, elastic constants, misfit volumes) that can be determined ab-initio or experimentally. The reduced theory enables screening over 10 million compositions in the whole Al-Cr-Mo-Nb-Ta-W-V-Ti-Zr-Hf alloy family to find the strongest BCC HEAs.

References

1. O.N. Senkov, G.B. Wilks, J.M. Scott, D.B. Miracle (2011) Mechanical properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 refractory high entropy alloys, Intermetallics 19, 698-706.

2. B. Cantor (2014) Multicomponent and High Entropy Alloys, Entropy 16, 4749-4768.

3. C. Lee, F. Maresca et al., Strength can be controlled by edge dislocations in refractory high-entropy alloys, Nature Communications 12:5474, 2021.

4. F. Maresca and W.A. Curtin, Mechanistic origin of high strength in refractory BCC high entropy alloys up to 1900K, 182:235–249, 2020.