Effects of additional Ag on the thermal stability and glass-forming ability of Cu–Zr binary glassy alloys

Abstract

Thermal stability and glass-forming ability (GFA) of (Cu 0.5Zr 0.5) 100− x Ag x ( x = 0–16) glassy alloys have been studied. Both of the supercooled liquid region (Δ T x ) and the GFA greatly increase with increasing Ag content. The largest Δ T x of 80 K and the critical diameter ( d c) of 6.0 mm were obtained for x = 12 and 10 alloys, respectively, and then decrease with further increasing Ag content. The substitution of Hf for Zr in Cu 45Zr 45Ag 10 glassy alloy increases the stability of supercooled liquid and fracture strength, though the GFA decreases. The substitution of Al for Ag in Cu 45Zr 45Ag 10 alloy is effective for the increase in Δ T x as well as GFA. The largest Δ T x of 86 K and d c of 9.0 mm were obtained for Cu 45Zr 45Al 5Ag 5 alloy. The GFA of the Cu–Zr-based alloys has better correlation with reduced glass transition temperature and γ value. The new bulk glassy alloys exhibit high fracture strength of 1774–2000 MPa with distinct plastic strains of 0.002–0.014.