Positron Lifetime Study on Degradation of TiCrV Hydrogen Storage Alloy

Using positron lifetime spectroscopy, we examined the evolution of defects in the Ti24Cr36V40 alloy prepared by arc-melting method during hydriding cycles. We found that the positron lifetime increases with increasing the pressure swing cycles. This behavior is well correlated with the degradation of hydrogen transfer change with the pressure swing cycles. The prolonged positron lifetime is attributed to dislocation-related defects. Both dislocations and vacancies bound at dislocations may act as positron trapping centers. After the heat treatment at 400oC, a partial recovery of positron lifetime was observed.