Formation, structure, and crystallization of Al-rich metallic glasses

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Abstract
The formation, structure, and the crystallization of Al85YxNi15−x are studied using x-ray diffraction and differential scanning calorimetry. The results show two distinct glasses depending on composition. Y-rich glasses (x≥8) are homogeneous with a well-defined glass transition. The x-ray diffraction patterns have a single main peak. These glasses crystallize through a nucleation and growth process. Y-poor glasses (x<8) do not show a glass transition and have a shoulder on the high-angle side of the main peak in their x-ray diffraction patterns. We show that the shoulder peak is due to quenched-in Al nuclei. These glasses are shown to crystallize through the growth of these nuclei. Y-rich glasses (x≥8) are more stable as demonstrated by the presence of the glass transition and their higher crystallization temperature, enthalpy, and activation energy. The occurrence of a prepeak for all compositions is attributed to Y-Y pairs.