Abstract
The influence of oxygen impurities on the crystallization mechanism of NiZr2 metallic glasses was studied. For this glass system, the first crystallization product is the metastable E93(cF96) cubic structure instead of the equilibrium C16(tI12) tetragonal structure. A possible mechanism for the formation of this metastable phase has previously been put forth. The hypothesis is that oxygen forms a semipermanent bond with Zr resulting in the oxygen atom being surrounded by six Zr atoms in octahedral configuration which act as nucleation sites for the E93 cubic phase. Hydrogenation of the amorphous composition eliminates the nucleation sites required for the formation of this metastable cubic phase, thereby allowing the glass to crystallize directly into the stable tetragonal C16 phase, and thus providing strong evidence in support of the proposed crystallization mechanism.
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