A NEW METASTABLE PHASE NEAR 60 AT-PERCENT ZR FROM AMORPHOUS NI-ZR

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 yields metastable crystalline phase yields NiZr//2 plus NiZr. The metastable Ni//4//0Zr //6//0 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 NiZr//2 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.