Bulk metallic glass formation in binary Cu-rich alloy series -: Cu100-xZrx (x=34, 36 38.2, 40 at.%) and mechanical properties of bulk Cu64Zr36 glass

The compositional dependence of a glass-forming ability (GFA) was systematically studied in a binary alloy series Cu100-xZrx (x = 34, 36, 38.2, 40 at.%) by the copper mold casting method. Our results show the critical casting thickness jumps from below 0.5 mm to above 2 mm when x changes from 34 to 36 while further increase in x reduces the critical casting thickness. The best glass former Cu64Zr36 does not correspond to either the largest undercooled liquid region (DeltaT = T-x1 - T-g, where T-g is the glass transition temperature. and T,1 is the onset temperature of the first crystallization event upon heating) or the highest reduced glass transition temperature (T-rg = T-g/T-1. where T-1 is the liquidus temperature). Properties of bulk amorphous Cu64Zr36 were measured, yielding a T-g similar to 787 K, T-rg similar to 0.64, DeltaT similar to 46 K, H-v (Vicker's Hardness) similar to742 kg/mm(2), Young's Modulus similar to92.3 GPa, compressive fracture strength similar to2 GPa and compressive strain before failure similar to2.2%. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.