Modelling solid solution hardening in high entropy alloys

Toda-Caraballo, Isaac and Rivera-Díaz-Del-Castillo, Pedro E.J. (2015) Modelling solid solution hardening in high entropy alloys. Acta Materialia, 85. pp. 14-23. ISSN 1359-6454

Abstract

Solid solution hardening (SSH) is one of the major contributions to the excellent mechanical properties displayed by high entropy alloys (HEAs). SSH is first analysed for binary systems in face-centred cubic and body-centred cubic alloys with different elemental additions in the temperature range 5-623 K. The prediction of the SSH has been possible by using Labush's approach for SSH modelling, where the necessary parameters have been incorporated without fitting to experimental data. Among these parameters, elastic misfit is shown to be prominent; experimental evidence suggests it has a dominant effect with respect to other misfit forms. Nevertheless, Labush's approach cannot be directly applied to model SSH in HEAs, since it is based on the misfit produced in the lattice of a solvent/reference atom, which does not exist in HEAs. Its extension to HEAs has been performed by using Mooren's approach for the computation of interatomic spacing in multicomponent alloys, allowing the creation of a model for elastic misfit in HEAs. This has led to a methodology for computing SSH effect in HEAs, where the results have successfully been compared with a collection of experimental data from the literature. The explanation of how different atoms can modify the yield strength can be formulated in terms of this approach.