Unusual glass-forming ability of bulk amorphous alloys based on ordinary metal copper.

We report the unusual glass-forming ability (GFA) of a family of Cu-based alloys, Cu46Zr47-xAl7Yx (0<x< or =10, in at. %), and investigate the origin of this unique property. By an injection mold casting method, these alloys can be readily solidified into amorphous structures with the smallest dimension ranging from 4 mm up to 1 cm without detectable crystallinity. Such superior GFA is found primarily due to the alloying effect of Y, which lowers the alloy liquidus temperature and brings the composition closer to a quaternary eutectic. Other beneficial factors including appropriate atomic-size mismatch and large negative heat of mixing among constituent elements are also discussed.