Solid State Formation and Properties of Bulk Amorphous and Nanocrystalline Refractory Metal-Based Alloys

摘要

The goals of our research are to understand solid-state amorphoization that accompanies the early stages of phase separation in multinary titanium-based alloys, to apply the concept of solid-state amorphization to other bulk alloys, and to study bulk-glass formability and devitrification in aluminum-based alloys. State-of-the-art electron microscopy, x-ray diffraction, and differential scanning calorimetry are utilized to perform the research. Effects on glass formability due to atomic size and interaction factors have been studied. Influence of the latter on the liquidus temperature of multi-component alloys and subsequently the overall effects on glass formability are investigated. Several phase diagrams of multinary aluminum-based alloys that exhibit deep-eutectics have been identified. Meanwhile, devitrification studies have been performed using detailed thermal and microstructural characterization. New results on the crystallization of aluminum-glasses have revealed the tendency toward forming nanoscale aluminum- rich clusters in the liquid state in the most easily formed aluminum-glasses. Currently, a semi-quantitative algorithm based on knowledge about binary and ternary systems is being developed to facilitate the screening of multinary alloys. Toward the end of our current ARO funding period, we have begun to extend the work to include aluminum-magnesium base multinary alloys.