FORMATION MECHANISM OF MGH2 AT LOW-TEMPERATURES IN TI0.6ZR0.4MN0.8CRCU0.2-(MG+MG2CU)

We have investigated the hydriding properties and the microstructures of the composite materials Ti0.6Zr0.4Mn0.8CrCu0.2-(Mg + Mg2Cu) produce d by liquid-phase sintering. The hydrogen capacities of the composite materials are larger than that of the host compound (Ti-Mn-based compo und), indicating that MgH2 is formed at 353 K. The amount of MgH2 is p roportional to that of the Mg-Mg2Cu eutectic phases in the composite m aterial. Observations of the microstructure for the etched composite m aterials using scanning electron microscopy reveal that MgH2 is formed near the interface between the host compound or Mg2Cu and the Mg regi on. Furthermore, MgH2 is formed easily in the Mg region far from the h ost compound. This simply suggests that hydrogen diffuses from the hos t compound into the Mg region along or through the Mg2Cu phase.