A new metastable phase near 60 at% Zr from amorphous Ni-Zr

Abstract

Metallic glass alloys of Ni-Zr were prepared by vapour and liquid quenching. For glass compositions at and near 60 at% Zr, crystallization proceeded by the sequence: amorphous → metastable crystalline phase → NiZr₂ + NiZr. The metastable Ni₄₀Zr₆₀ phase exhibited a very distinctive X-ray diffraction pattern and was present in both liquid- and vapour-quenched samples. Long-term anneals of samples with the metastable structure produced the equilibrium phases NiZr₂ and NiZr. The crystallization of the amorphous structure directly to a single metastable phase shows a correspondence between the compositions of the amorphous and crystalline phases. These results thus suggest a connection between the short-range structure of the glassy phase and the crystalline phases to which they transform. An observation of peaks and valleys in a plot of the X-ray scattering vector,Q _p, against glass composition is noted.