On the Optimal Glass-Forming Composition of Al–Co–Y Amorphous Alloys

Abstract

Al–Co–Y alloys were suction cast under identical conditions into a wedge-shaped copper mold for investigating the compositional dependence of glass-forming ability (GFA). The optimal glass-forming composition was determined to be Al₈₉Co_5.5Y_5.5, whose Al content is evidently larger than the findings of the optimal glass formers in other Al–TM–Y alloy systems. A reason is that Co-centered clusters tend to share vertexes and edges rather than faces with the surrounding clusters in Al–Co–Y amorphous alloy, and more Al atoms are required. When Al₈₉Co_5.5Y_5.5 amorphous alloy and its neighbors were isochronally annealed in a differential scanning calorimeter, no glass transition could be observed and the primary crystallization phase was invariably fcc-Al.