Cu-based bulk glassy alloys with good mechanical properties in Cu-Zr-Hf-Ti system

M.-h-strength Cu-based bulk glassy alloys were synthesized in Cu-Zr-Ti and Cu-Hf-Ti ternary and Cu-Zr-Hf-Ti quaternary systems by copper mold casting. The critical diameter was 4 mm for the Cu60Zr30Ti10 and Cu60Hf25Ti15 ternary alloys and the Cu60Zr20Hf10Ti10 and Cu60Zr10Hf15Ti15 quaternary alloys. As the substitution amount of Zr or Hf by Ti in Cu60Zr40 and Cu60Hf40 alloys 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-i) has a minimum of 1127 K around 20%Ti, resulting in a maximum T-g/T-i of 0.63 in the vicinity of 20%Ti. The high glass-forming ability was obtained at the compositions with high Tg/T-i. The bulk glassy alloys exhibit high fracture strength of 2040-2190 MPa and plastic elongations of 0.3 to 1.9% The finding of the Cu-based bulk glassy alloys with high T-g/T-i above 0.60, high fracture strength above 2000 MPa and distinct plastic elongation is encouraging for the subsequent development as a new type of bulk glassy alloys which can be used for structural materials.