Laves-phase formation criterion for high-entropy alloys

In this study, we have analysed Laves-phase formation in high-entropy alloys (HEAs). For that purpose, the AlCrxNbTiV and AlxCrNbTiVZr (x = 0, 0.5, 1, 1.5) alloys were produced and examined. It was found that the AlNbTiV and AlCr0.5NbTiV alloys had single-phase body-centred cubic structure, while the other alloys contained Laves phase. Analysis has demonstrated that Laves-phase formation in the produced and in the other HEAs, which are predominantly composed of Al and the elements of 4–6 groups and tend to form body-centred cubic solid solutions, can be predicted by the atomic size mismatch, δr, and the Allen electronegativity difference, ΔχAllen, parameters. It was shown that Laves-phase formation is observed when δr > 5.0% and ΔχAllen > 7.0%.