Cu-based bulk glassy alloys with high tensile strength of over 2000 MPa

Cu-based glassy alloys with tensile strength of over 2000 MPa were synthesized in Cu-Zr-Ti and Cu-Hf-Ti ternary and Cu-Zr-Hf-Ti and Cu-Zr-Ti-Y quaternary systems by copper mold casting. The critical diameter was 4 mm for the Cu60Zr30Ti10 and Cu60H25Ti15 ternary alloys and the Cu60Zr20Hf10Ti10 and Cu60Zr10Hf15Ti15 quaternary alloys and 5 mm for the (Cu0.6Zr0.3Ti0.1)(98)Y-2 alloy. As the Ti content increases, the glass transition temperature (T-g), crystallization temperature (T-x) and temperature interval of supercooled liquid region, DeltaT(x)(=T-x - T-g), decrease, while the liquidus temperature (T-l) has a minimum of 1127 K around 20% Ti, resulting in a maximum T-g/T-l of 0.63 in the vicinity of 20% Ti. The bulk glass-forming ability was obtained at the compositions with T-g/T-l > 0.60. The glassy alloys have a fracture strengths between 2050 and 2160 MPa and plastic elongations of 0.8-1.7%. The finding of the Cu-based bulk glassy alloys with T-g/T-l > 0.60, fracture strength >2000 MPa and plastic elongation indicates a possibility for subsequent development of glassy alloys with new compositions which can be used for structural materials. (C) 2002 Published by Elsevier Science B.V.