The solubility limit and mechanical alloying process in Ni-X, Cu-X (X=Ge, Ga, Al, In, Sn) systems

The mutual solid solubility of f.c.c. or b.c.c. metals can be extended by mechanical alloying (MA). As a result of disordering of the intermetallic structure, mutual solubility may be extended through regions in which equilibrium cubic structures are stable. The existence of an equilibrium non-cubic structure prevented a further increase in concentration in the MA cubic solid solutions. However, the formation of an extended solid solution by MA may proceed through the formation of an intermetallic compound. Several systems with existing equilibrium intermetallic compounds( with cubic or non-cubic structures) have been chosen in order to study the extension of solid solution stability by MA. The first set of systems: Ni-Sn,In, Cu-Sn,In form equilibrium solid solutions at high temperatures. During MA of Ni-Ge and Ni-Ga, the solid solution ranges were extended through regions in which equilibrium cubic structures are stable. The equilibrium non-cubic structure, for example at 27 at% Ge, or in case of Ni-Sn and Ni-In prevented a further increase in concentration of the cubic solid solutions. Conversely, in Ni-Ge,Ga, Cu-Ga,Al systems there is considerable solid solubility at room temperature. These systems show the formation of the extended solid solutions was preceeded by the formation of the equilibrium intermetallic phases.