HYDRIDING PROPERTIES OF A NANO- AMORPHOUS-STRUCTURED MG-NI-H SYSTEM/

The alloys Mg-x at.% Ni (x=33, 38, 43 and 50) with nanometer-scale str uctures were successively synthesized by mechanical grinding of Mg2Ni mixed with various amounts of additional Ni. The total hydrogen conten ts in these alloys increases from 1.7 mass% for x=33 to 2.2 mass% for x=43 and 50, while the dehydriding temperatures gradually lower from 4 40 K to 373 K with increasing of the Ni amounts. The value of the tota l hydrogen content in each alloy is reasonably explained by taking int o account the hydrogen contents of the following three regions; the in tra-grain region of nanostructured Mg2Ni, its inter-grain region, and the amorphous MgNi region. The maximum hydrogen content in the amorpho us MgNi region, 2.2 mass%, might imply a specific interatomic occupati on of hydrogen atoms in this region.