The e/a criterion for the largest glass-forming abilities of the Zr-Al-Ni(Co) alloys

Composition optimization for the largest glass-forming ability has been performed in the Zr-Al-Ni(Co) systems in this investigation. Two guiding criteria, termed respectively the e/a-constant criterion and the e/a-variant criterion, are applied. They are incarnated into the e/a = 1.5 composition line and the Zr₉Ni(Co)₄-Al composition line. Bulk metallic glasses are obtained by suction casting alloy melts of compositions within an e/a span of 1.3-1.5, with their thermal stabilities and glass forming abilities being increased with increasing e/a. The intersecting point of the two lines gives the composition Zr₅₃Al_23.5Ni(Co)_23.5 with the largest glass-forming ability.