Microstructure and mechanical performances of novel multi-phase refractory high entropy alloys in Ti-Zr-V-Mo fabricated by vacuum arc melting

In this work, four novel refractory high entropy alloys (RHEAs) of the Ti-Zr-V-Mo system have been developed and characterized by experiments. Except for the RHEA of Ti0.5ZrVMo with phase constituents of bcc + pm-3n + Laves (C15 type), the phase constituents in the as-solidified condition of all the other three RHEAs can be denoted as bcc1 + bcc2 + Laves (C15 type). All four alloys exhibited typical dendrite morphology with coarse dendrites and thin inter-dendritic regions. Besides, there were certain smallsized precipitated particles dispersed in the inter-dendrite matrix. In TiZrV3Mo, bcc structured solid solution phases of (TiMoV) and (TiZrV) as well as one C15 Laves phase of (MoV) Zr were confirmed. The equiatomic RHEA of TiZrVMo exhibited a yield strength of 1323.0 MPa, compressive strength of 1521.9 MPa and a compressive strain of 4.5%, also with double bcc structured solid solution phases of (TiMo) and (TiZr) as well as the Laves precipitate of Zr0.5Ti0.5Mo2. The multi-phase RHEAs with solid solutions and minor precipitates with excellent performances by deformation incompatibility between phases, provide a certain reference for the composition design and the industrial devel-opment of RHEAs in practical applications.