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 HfMoTaTiZrCr0.5 is 535.8 Hv0.3, 56.96% higher than the reference alloy HfMoTaTiZr. The yield strength and fracture strain of HfMoTaTiZrCr0.5 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 HfMoTaTiZrCr0.5 results in the improvement in ductility.