2003 Volume 44 Issue 11 Pages 2346-2349
The supercooled liquid region defined by the difference between glass transition temperature (Tg) and crystallization temperature (Tx), ΔTx(=Tx−Tg) for Cu50Hf45Al5 glassy alloy increased by the addition of noble metals (Ag, Pd, Pt or Au) and the largest ΔTx reached 110 K for Cu45Hf45Al5Ag5. The large ΔTx of 94 to 101 K were also obtained for the alloys containing the other noble metals of 5 at%. The reduced glass transition temperature (Tg⁄Tl) of Cu45Hf45Al5M5 (M=Ag, Pd, Pt or Au) glassy alloys are in the range from 0.60 to 0.61. The selection of the quaternary compositions enabled us to form bulk glassy alloys with diameters up to 3 mm. The Vicker’s hardness, Young’s modulus, compressive fracture strength and plastic strain are 603 to 655, 119 to 125 GPa, 2220 to 2330 MPa and 0.1 to 0.6%, respectively, for the Cu45Hf45Al5M5 (M=Ag, Pd, Pt or Au) bulk glassy alloys. A different crystallization behavior is observed for Cu50Hf45Al5 and Cu45Hf45Al5Ag5 glassy alloys. The final crystallization phases are Cu10Hf7 and CuHf2 for the former alloy, and Cu10Hf7, CuHf2 and Cu8Hf3 for the latter alloy.