Glass-forming ability and thermal stability of (Gd-Tb)-Al-Co glass alloys

Glass-forming ability (GFA) in (Gd-Tb)-Al-Co system were evaluated. The melting and solidification characteristics of corresponding alloys were determined by differential scanning calorimeter. The results of glass formation and thermal analysis reveals that the binary rare-earth based metallic glass alloys, (Gd-Tb)-Al-Co, have higher GFA than single rare earth based alloys, Gd-Al-Co or Tb-Al-Co. The (Gd_0.5Tb_0.5)₅₅ Al₂₅Co₂₀ alloy, which has the highest GFA with the critical diameter of 5mm by copper mold casting, is on the steep side of liquidus surface and near the eutectic point. Compared with Gd₅₅Al₂₅Co₂₀ and Tb₅₅Al₂₅Co₂₀, the coexistence of Gd and Tb decreases the solidification temperature of the corresponding alloys, consequently stabilize the liquidus structure and improve the GFA of the resulting alloys.