Interstitial strengthening of refractory ZrTiHfNb_0.5Ta_0.5O_x (x = 0.05, 0.1, 0.2) high-entropy alloys

This paper investigates the microstructure and mechanical properties of ZrTiHfV_0.5Nb_0.5O_x (x = 0.05, 0.1, 0.2) alloys. The ZrTiHfNb_0.5Ta_0.5 alloy has single body-centered cubic (BCC) phase structure. No oxide phases are detected and the diffraction peak (1 1 0) shifts to the left apparently when oxygen is added. Only one set of diffraction spots is observed in the patterns of selected area electron diffraction. The above results confirm that oxygen atoms dissolve into the lattice of ZrTiHfNb_0.5Ta_0.5 alloy. The increase in oxygen content is accompanied by an interstitial strengthening effect at both room temperature and high temperature, but a decrease in compressive ductility. This new method to enhance the mechanical properties of refractory high-entropy alloys is discussed.