Stability of amorphous transition-metal films

Abstract

We have observed the temperature stability of the amorphous structure in many transition-metal-alloy systems (Nb-Mo, Ta-W, Nb-Zr, Mo-Ru, W-Re, Mo-Rh, Ta-Re, Zr-Mo, Ta-Ir, and Zr-Ru) prepared by electron-beam evaporation onto liquid-helium-cooled substrates. Past observations which established criteria for the formation of amorphous metallic alloys were largely limited to close-packed elements. In this paper, which includes a large number of bcc elements, we find that the crystalline-state immiscibiltiy of the elements is a stronger factor in determining the stability, as well as the ease of formation of the amporhous structure, than is the difference in atomic size of the constituent elements.