Unusual Glass-Forming Ability of Bulk Amorphous Alloys Based on Ordinary Metal Copper

Abstract

We report the unusual glass-forming ability (GFA) of a family of Cu-based alloys, ${\mathrm{Cu}}_{46}{\mathrm{Zr}}_{47-x}{\mathrm{Al}}_7{\mathrm{Y}}_x$ ($0<x\le 10$, 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.