Synthesis of Mg-Fe bcc Alloys by Mechanical Alloying and Their Hydrogen Solubility

Mg-Fe bcc alloys were synthesized by mechanical alloying under argon atmosphere. The bcc lattice parameters of synthesized alloys with composition less than 15 mol% of Mg were expanded. It suggests that larger Mg atoms were dissolved into the Fe bcc lattice. Lattice parameter of bcc decreased with higher Mg composition, from 20 mol% to 50 mol%. The results from SEM and TEM images implied that Mg and Fe were separated when increasing Mg concentration. As the result, the bcc lattice parameter relaxed to nearly that of pure iron. P-C isotherms of MgxFe1-x(x=0-0.5) were determined at 523 K. It was found that plateau pressures decreased with the increasing Mg composition. In this study, the Mg-Fe alloys with different compositions were synthesized and their hydrides stability was discussed from viewpoints of both “interstitial size effect” and “metal-hydrogen inter-atomic bonding”.