Electron microscopy and hydriding properties of MgYNi4 synthesized by mechanical alloying

The ternary alloy, MgYNi4, was synthesized by mechanical alloying (MA). Its microscopic structures and hydriding properties were studied. The annealing of the alloy at 773 K was also studied. The alloy consists of nanocrystals of less than 10 nm in diameter. The capacity of the hydrogen atoms in the alloy increases with the increasing size of the nanocrystals. The crystal structure was found to be the C15 type Laves phase structure for the MA-treated alloy, while crystal structure of the as annealed alloy was the ordered C15 type structure which is conventionally called C15b type and is formally called AuBe5 type structure. The hydrogen capacity in the alloy might have a strong relation to the atomic arrangement of this alloy. (C) 2002 Elsevier Science B.V. All rights reserved.