A theoretical analysis of the glass-forming behaviour of Ni-Zr and Ni-Zr-Fe alloys

The metastable free energy diagram of the Ni-Zr alloy at 300 K was calculat ed using Miedema's theory. A previous extension of the theory to ternary sy stems was further developed and used to calculate the free energies of the metastable amorphous phase and crystalline solid solutions of the Ni-Zr-Fe system at 300 K. The results of the calculations are compared with experime ntal data taken from the literature. The metastable free energy diagram of Ni-Zr is consistent with the measured glass-forming range. It allows to pre dict the succession of phases - amorphous alloys, crystalline solid solutio ns and intermetallic compounds - observed in rapidly quenched Ni-Zr alloys and in solid-state interdiffusion in Ni-Zr composites. In the ternary syste m Ni-Zr-Fe, intersections of the calculated free-energy surfaces of solid s olutions together with that of the amorphous phase define an extended glass -forming composition range that contains the observed Ni-Zr-Fe glass compos itions. The relative positions of the free-energy surfaces of the bcc solid solution and the amorphous phase and the region of metastable equilibrium between amorphous alloy and alpha-Zr solid solution provide the basis for i nterpreting the appearance of different phases in experiments on partial am orphization of Zr-rich, Ni-Zr-Fe melt-quenched alloys.