In Ti–Zr–Mn–Cr–Fe alloys, increased non-stoichiometric Mn and Cr raises the equilibrium plateau pressure, flattens the plateau region, and slightly reduces hydrogen content. The optimized x = 0 with y = 0 alloy maintains 96.2% capacity retention after 500 hydrogenation–dehydrogenation cycles.

The influence of alternating current (AC) field on the pack boriding process for medium carbon steel was investigated through characterization of microstructure, phase composition, microhardness, and corrosion resistance of the boride layer and its mechanism was revealed. Results showed that the boride layer obtained by AC field boriding was composed of the outer FeB and the inner Fe₂B phase, which was similar to that of conventional boriding. Meanwhile, the effective thickness of the boride layer and proportion of Fe₂B increased gradually with increasing current during AC field boriding. The introduction of an AC field during the boriding process served dual purposes. First, it facilitated the decomposition of the boriding medium, leading to an elevation in the concentration of active boron atoms. Second, it reduced the activation energy required for atomic diffusion, thereby accelerating the diffusion of both boron and iron atoms. These combined effects significantly enhanced the hardness distribution and corrosion resistance of the steel. Further insights into the process were gained by fitting the parabolic kinetics curves, which confirmed that the boriding process in an AC field was exclusively controlled by diffusion. This study also clarified the growth mechanism of the boride layer within an AC field.