FORMATION OF METAL-HYDRIDES BY MECHANICAL ALLOYING

Metal hydrides (TiH1.9, delta-ZrH1.66, and MgH2) have been synthesized by mechanical alloying of metal powders in a hydrogen atmosphere at room temperature. The milling process was monitored using H-2 pressure measurement. The sharp decrease in H-2 pressure during milling indicates a high rate of H-2 absorption into the metal powders. X-ray diffraction analysis of as-milled powders shows convertion to hydrides at short milling times (less than 6 h). Decomposition of the so-formed metal hydrides has been observed during thermal analysis. The results indicate that pulverization and deformation processes occurring during high energy ball impacts play a major role in the hydriding reaction.