The effect of Sc addition on the hydrogen storage capacity of Ti _0.32Cr_0.43V_0.25 alloy

The effect of the addition of 4th element on the hydrogen storage capacity of Ti_0.32Cr_0.43V_0.25 alloy was evaluated by simulation and confirmed experimentally. The crystal lattice volume, phase formation energy, and hydrogen absorption energy of the alloys were calculated by ab initio calculation for the alloys containing the third-period transition metals as Sc, Cr, Mn, Fe, Co, Ni, Cu, and Zn. It was postulated that the hydrogen absorption would be favored by large crystal volume and low hydrogen absorption energy. The calculation suggested Sc as the most suitable element and the hydrogen capacities of a series of Ti_0.32Cr _0.43-xV_0.25Sc_x alloys (x = 0.02-0.1) were determined accordingly. Among the alloys, the capacities of Ti _0.32Cr_0.41V_0.25Sc_0.02 and Ti _0.32Cr_0.39V_0.25Sc_0.04 alloys were higher than that of the Ti_0.32Cr_0.43V_0.25 alloy. The capacity of both alloys could be enhanced further by the heat treatment at 1250 °C due to the elimination of the second-phase TiCr ₂.