Effect of the alloying element titanium on the stability and trapping of hydrogen in pure vanadium: A first-principles study

With a first-principles method based on density functional theory, the effect of the alloying element titanium (Ti) on the thermodynamic stability and electronic structure of hydrogen (H) in pure vanadium (V) is investigated. The interactions between H and the vacancy and the defect solution energies in a dilute V-Ti binary alloy are calculated. The results show that: (i) a single H atom prefers to reside in a tetrahedral interstitial site in dilute V-Ti binary alloy systems; (ii) H atoms tend to bond at the vacancy sites; a mono-vacancy is shown to be capable of trapping three H atoms; and (iii) the presence of Ti in pure V can increase the H trapping energy and reduce the H trapping capability of the vacancy defects. This indicates that doping with Ti to form dilute V-Ti binary alloys can inhibit the solution for H, and thus suppress the retention of H. These results provide useful insight into V-based alloys as a candidate structural material in fusion reactors.