High-strength Cu-based bulk glassy alloys in Cu-Zr-Ti-Be system

New Cu-based bulk glassy alloys with high glass-forming ability and good mechanical properties were formed in Cu-Zr-Ti-Be system. The glass transition temperature (T_g), supercooled liquid region defined by the difference between crystallization temperature (T_x) and T_g, ΔT_x(= T_x - T_g) and reduced glass transition temperature (T_g/T_l) are 728 K, 50 K and 0.64, respectively, for the (Cu_0.6Zr_0.3 Ti_0.1)_92.5 Be_7.5 and 720 K, 42 K and 0.64, respectively, for the Cu₅₄Zr₂₇ Ti₉ Be₁₀ alloy. The use of the 7.5%Be and 10%Be alloys has enabled us to form glassy alloy rods with diameters up to 5 mm. The bulk glassy 10%Be alloy exhibits high tensile fracture strength of 2450 MPa and Vickers hardness of 710, in combination with Young's modulus of 146 GPa, compressive fracture strength of 2500 MPa and compressive elongation of 3.5%. The tensile strength level is the highest among all bulk metallic glasses and hence the new Cu-based bulk glassy alloys have significant importance in basic science and engineering aspects.