Cobalt- and copper-substitution effects on thermal stabilities and hydriding properties of amorphous MgNi

Amorphous (a-)Mg(Ni1-xTx) with T=Co and Cu were formed by mechanical alloying in the composition range x=0-0.5. The crystallization temperatures increase/decrease by Co/Cu substitution, while the enthalpies of amorphous formation are little changed by substitution. On the other hand, the p-e isotherms indicate that the hydrogen-site energies become partially unstable with substitution. The relation between the enthalpy of amorphous alloy formation and subsequent hydride formation is discussed quantitatively on the basis of thermal analysis and the rule of reversed stability. (C) 1998 Elsevier Science S.A. All rights reserved.