Amorphous Ni-Zr Phase Formation in Self-Supporting Thin-Film Lateral-Diffusion Couples

Abstract

AbstractThe formation of an amorphous Ni-Zr alloy, by heating to cause interdiffusion in the temperature range 250°C to 325°C, was demonstrated in a self-supporting lateral-diffusion couple. Micro-area diffraction in a scanning transmission electron microscope (STEM) indicates that microcrystalline ordering in the amorphous phase must be on a scale less than 5 nm. The samples were heated in a vacuum furnace to form the amorphous phase and later heated in the STEM for in situ observation of crystalline compoundformation. The amorphous to crystalline transformation occurs first in theZr-rich regions at 370°C. A crystalline phase begins to consume the Ni rich amorphous material, at 450° C; but at 325° C, the amorphous phase is stable up to 20.5 hours, even in the presence of crystalline compounds.