Enhanced glass forming ability and mechanical properties of new Cu-based bulk metallic glasses

The thermal stability, glass forming ability and mechanical properties of Cu-Zr-Al-M (M = Ag, Be) bulk metallic glass alloys have been investigated. The glass forming ability in the Cu-Zr-Al-M (M = Ag, Be) alloys increased proportionally to the Ag or Be content and show good correlations with thermal parameters such as ΔT_x (=T_x - T_g), T_rg (=T_g/T_l) and γ (=T_x/(T_g + T_l)), where T_g, T_x, and T_l are glass transition, crystallization, and liquidus temperatures, respectively. Particularly, for the Cu₄₃Zr₄₃Al₇Be₇ alloy, the supercooled liquid region reached 103 K, and fully amorphous rods up to 12 mm in diameter were successfully fabricated by copper mold casting. Ag containing alloy shows large ductility due to phase separation and Be containing alloy shows high compressive strength due to high packing density.