Superior glass-forming ability of CuZr alloys from minor additions

We report a novel phenomenon in which minor element additions (∼1 at.%) can dramatically enhance the glass-forming ability (GFA) of CuZr(Al) metallic alloy, which can be cast into glasses with large cross-section sizes using a conventional casting method. The minor additions cause the liquidus temperature T_l to decrease from 1219 (for Cu₅₀Zr₅₀) to 1139 K [for (Cu₅₀Zr₅₀)₉₂Al₇Gd₁], and the reduced glass transition temperature T_rg (=T_g/T_l) of the alloys increases from 0.550 (for Cu₅₀Zr₅₀) to 0.613 [for (Cu₅₀Zr₅₀)₉₂Al₇Gd₁]. The mechanism involved in the achievement of the superior GFA is explained by the stronger tendency of short-range ordering in the stronger microalloyed alloys as well as the thermodynamic and kinetic aspects.