Two refractory high-entropy alloys CrHfNbTaTi and CrHfMoTaTi: Phase, microstructure and compressive properties

Two new refractory high-entropy alloys, CrHfNbTaTi and CrHfMoTaTi, deriving from the well-known HfNbTaTiZr alloy by principal element substitutions, were prepared by vacuum arc-melting. Their phase components, microstructures, and compressive properties in the as-cast state were investigated intensively. The results showed that both alloys are mainly composed of a BCC and cubic laves phase. In terms of the mechanical properties, the yield strength increased remarkably from 926 MPa of HfNbTaTiZr to 1258 MPa of CrHfNbTaTi, meanwhile a promising ductility of around 24.3 % elongation was retained. The morphology and composition of the network-shape interdendritic regions were closely related to the improvement in mechanical properties deduced by elemental substitution. Whereas, dendritic surrounded by the incompact interdendritic shell at the case of the incorporation of Mo deteriorates the yield strength, and results in a typical brittle feature.