Microstructure and Mechanical Properties of WMoNbCrTi HEAs Sintered from the Powders Milled for Different Durations

Refractory high-entropy alloys (HEAs) are reported to have better properties than conventional alloys. In this work, a new refractory WMoNbCrTi HEA was spark plasma sintered with ball milling powder. The results show that the microstructure and mechanical properties of the bulk alloys are strongly dependent on the milling duration of the powders. The structure of the powders milled for 5-40 h is mainly composed of three BCC solid solution phases (W-rich, Nb-rich and Cr-rich). After being consolidated by SPS, the structure of the bulk alloys consists of a W-rich solid solution matrix with a small amount of Ti-rich solid solution and Laves phase. The WMoNbCrTi HEA prepared from 30 h milling powder shows the highest hardness value of 10.40 GPa. However, the alloy prepared from the 5 h milling powder exhibits the maximum fracture toughness (7.16 MPa m(1/2)), compressive fracture strength (2765 MPa) and fracture strain (9.8%), respectively. The reasons for the influence of the milling duration on the mechanical properties of the WMoNbCrTi HEAs are discussed in detail. The combination of mechanical alloying and the subsequent sintering is a promising way to fabricate HEAs with controllable mechanical properties.