Protium absorption-desorption properties of Ti-Cr-Mo bcc solid solution alloys

We have investigated the protium absorption-desorption properties of Ti-Cr-Mo alloys of varying composition, including cycling-induced effects. The capacity of alloys with less than 10 at% Mo has an H/M ratio of 1.8 at 10 MPa hydrogen pressure, and remains almost unchanged regardless of Mo content. The 40Ti-Cr-2.5Mo alloy has the widest plateau region observed in this study. The amount of protium desorption and the mean particle size vary inversely with the logarithm of cycle number up to 300 cycles. The capacity of the alloy is drastically affected by the conditions of cycling. With longer evacuation times the capacity decreases significantly. The lattice parameter of the β protide increases with increasing cycles, and the reflection peaks in XRD studies are broadened. The reduction in capacity after several absorption-desorption cycles is somewhat restored by annealing at 673 K for 2 h under vacuum. The absorption pressure of the plateau for the 101st cycle, after annealing following the 100th cycle, recovers to that of the plateau for the first cycle, but then decreases with additional cycling.