Effect of Mo content on hydrogen storage properties and cyclic stability of BCC-type TiCrMo alloys

BCC-type Ti–Cr–Mo alloys are low-cost and promising alternatives to vanadium-based hydrogen storage alloys, but their insufficient cyclic stability severely limits practical applications. In this work, single-phase BCC Ti–Cr–Mo alloys with different Mo contents were fabricated by vacuum arc melting combined with water quenching. The results indicate that increasing Mo content significantly enhances the structural stability of the alloys. Synergistically regulated by lattice parameters and bulk modulus, the maximum hydrogen storage capacity decreases from 3.5 wt% to 3.09 wt%, while the capacity retention after 50 cycles increases from 74.6% to 88.9%. HR-TEM and TDS analyses confirm that Mo addition effectively suppresses local amorphization and irreversible hydrogen trapping. Proper adjustment of Mo content can significantly improve cyclic stability while maintaining favorable hydrogen storage performance, providing an important basis for the compositional design of high-performance vanadium-free BCC hydrogen storage alloys.