Synergy of strength–ductility in HfMoTaTiZr refractory high entropy alloy through Cr addition

Abstract

Concurrent strength–ductility improvement of HfMoTaTiZr is achieved via Cr addition and the underlying strengthening mechanism was discussed. 4.2 at% Cr addition into HfMoTaTiZr led to the formation of a Laves phase, in addition to the BCC phase. The hardness of HfMoTaTiZrCr_0.5 is 535.8 Hv_0.3, 56.96% higher than the reference alloy HfMoTaTiZr. The yield strength and fracture strain of HfMoTaTiZrCr_0.5 reach 1750.6 ± 80.3 MPa and 14.0 ± 2.9%, respectively, 207.5 MPa and 20.6% higher than HfMoTaTiZr. Solid solution hardening and the presence of the intermetallic Laves phase are believed to be responsible for the enhancement in strength and the formation of a reticulated structure of the Laves phase in HfMoTaTiZrCr_0.5 results in the improvement in ductility.