Oxide Formation in a Melt Spun Alloy in the Zr-Ni-Cu System

The microstructure of a melt-spun Zr₂₈Ni₄₄Cu₂₈ (at. %) alloy was characterized in order to determine the structures and compositions of the crystalline phases that compete with glass formation during rapid solidification. Two crystalline phases were identified, namely, a face centered cubic (FCC) zirconium oxide phase and a primitive cubic version of the big-cube oxide phase, using a combination of scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscopy techniques. Our results indicate that the Zr-O atomic pair interaction is preferential compared to the other atomic pair possibilities, supporting the formation of Zr-based oxides over the equilibrium phases in the ternary Zr-Ni-Cu system. Further, the results provide insight into the mechanisms of oxygen-induced crystallization in Zr-based BMGs and the corresponding decrease in glass forming ability (GFA) with increasing oxygen concentrations.

Keywords:
Metallic glass; Zr-Ni-Cu system; zirconium oxide; big-cube