Microstructures and mechanical properties of TiZrHfNbTaWx refractory high entropy alloys

Refractory high-entropy alloys (RHEAs), which exhibit excellent mechanical properties at room temperature and high temperature, have received widespread attention. The TiZrHfNbTa alloy is one of the few refractory high-entropy alloys with tensile ductility. Alloying means is a common method to optimize the special properties of alloys. Here, a series of TiZrHfNbTaW x (x = 0–1) RHEAs were synthesized by arc melting technique. It showed that the fracture plasticity of the RHEAs changed from ＞50% of the TiZrHfNbTa to 20.7% of the TiZrHfNbTaW, and the yield strength increased from 1064 MPa of the TiZrHfNbTa to 1726 MPa of the TiZrHfNbTaW. In addition, The TiZrHfNbTaW x RHEAs predominantly consisted of a single random solid solution phase with body-centered cubic (BCC) crystal structure. The present result indicated that W addition could effectively enhance the strength of the TiZrHfNbTa alloy, while maintaining high plasticity. Finally, a simple solid solution strengthening theoretical model was proposed to explain the high yield strength, and the experimental values were in good agreement with the theoretical values. • A series of novel RHEAs with high strength and excellent plasticity was designed by alloying means. • It showed that the TiZrHfNbTaW RHEA has a yield strength of 1726 MPa and still maintains a compressive plasticity of 20.7%.. • A simple solid solution strengthening theoretical model was proposed to explain the high yield strength. • The experimental values were in good agreement with the theoretical values by solid solution strengthening model.