Microstructure and Mechanical Properties of WTaVCrTi Refractory High-Entropy Alloy by Vacuum Levitation Melting for Fusion Applications

In present study, vacuum levitation melting was utilized to produce WTaVCrTi refractory high-entropy alloy designed for high-temperature and nuclear fusion applications. Microstructure characterization, composition analysis, mechanical properties and thermal conductivity were presented by SEM, XRD, TEM, ICP-OES, compressive test, and laser-flash thermal analyzer. WTaVCrTi HEA was found to be a bimodal microstructure comprising of bcc crystal phase and minor secondary phase showing a fully-interfacial coherence with the bcc phase. The outstanding Vickers microhardness of the alloy is about five times higher than that calculated by the rule-of-mixture. Its compression yield strengths at room temperature (RT), 400, 600, and 800 °C were 1628, 1370, 1215, and 1055 MPa, respectively, exhibiting strong resistance to high-temperature softening. Fewer cleavage features were observed with increasing temperature compared to the fracture at RT. The remarkably reduced thermal conductivity of 16.8 W/m K at RT could contribute to defect recombination and outstanding resistance to irradiation. These enhanced strength, hardness, and irradiation resistance characters are promising for high-temperature structure and fusion applications.