COBALT-SUBSTITUTION 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 a lloying in the composition range x=0-0.5. The crystallization temperat ures increase/decrease by Co/Cu substitution, while the enthalpies of amorphous formation are little changed by substitution. On the other h and, the p-e isotherms indicate that the hydrogen-site energies become partially unstable with substitution. The relation between the enthal py of amorphous alloy formation and subsequent hydride formation is di scussed quantitatively on the basis of thermal analysis and the rule o f reversed stability. (C) 1998 Elsevier Science S.A. All rights reserv ed.