2003 Volume 44 Issue 9 Pages 1839-1844
The thermal stability of supercooled liquid in the temperature range before crystallization was examined in Zr55Al45−x−yCoxCuy alloys without Ni element and the large supercooled liquid region exceeding 80 K was obtained at the compositions around Zr55Al20Co20Cu5 and Zr55Al15Co7.5Cu22.5. By choosing the alloy composition of Zr55Al20Co20Cu5, we have formed bulk glassy alloys in rod and sheet forms by copper mold casting and melt-clamp die forging. The maximum diameter and sheet thickness were 5 mm and 3 mm, respectively. The Tg, ΔTx and Tg⁄Tl are 746 K, 84 K and 0.61, respectively, being independent of sample thickness. The bulk alloy sheet exhibits Young’s modulus of 92 GPa, elastic elongation limit of 2.1% and high tensile strength of 1960 MPa. These strength values are considerably higher than those for the other Zr-based bulk glassy alloys reported up to date. The synthesis of the new Zr–Al–Co-based bulk glassy alloy with high glass-forming ability, large supercooled liquid region and high tensile strength approaching 2000 MPa is expected to result in a future extension of application fields as a high strength material.