Effect of Zr content on hydrogen absorption and desorption properties of Ti_35-xV₂₅Cr₁₅Nb₂₅Zr_x (x = 0, 2, 4, 6, 8) high entropy alloys

Element regulation can enhance the hydrogen storage property of high-entropy alloys (HEAs). To investigate the effect of Zr element doping on the hydrogen ab/desorption properties of HEAs, Ti_35-xV₂₅Cr₁₅Nb₂₅Zr_x (x = 0, 2, 4, 6, 8) HEAs with different Zr contents were prepared. The hydrogen absorption capacity of Ti₂₉V₂₅Cr₁₅Nb₂₅Zr₆ alloy is 2.21 wt.% at 373 K. Due to the lattice distortion effect produced by the Zr substituting Ti optimizes the hydrogen absorption kinetics, improving the hydrogen absorption and desorption properties of HEAs. However, the hydrogen absorption decreases by about 11 % at 323 K due to the C14 Laves phase content increasing when the Zr content is 8 at.%. Therefore, when the Zr content <8 at.%, the lattice distortion enhances the hydrogen storage performance. Conversely, the increase of Zr content will promote the formation of C14 Laves phase reduces the maximum hydrogen storage capacity of HEAs.