Atomic size effect on the formability of metallic glasses

Abstract

The minimum solute concentration in a binary alloy system necessary to obtain a stable amorphous phase by rapid quenching, C B min, collected from the published reports on glass formation of 66 systems, was found to be inversely correlated with the atomic volume mismatch, | (v b −v A v A | , where v A is the atomic volume of the matrix and v B is the atomic volume of the solute. The atomic scale elasticity theory was developed to calculate the atomic level stresses in solid solution, which led to the stress criteria for the topological instability of solid solution. It was found that C B min is closely correlated with the critical solute concentration for the topological instability of solid solution. This result indicates that the atomic size ratio between the constituent elements is the most important factor in the determination of value of C B min, and the amorphous alloys are stabilized partly because the solid solutions of the corresponding compositions are topologically unstable.