Formation, thermal stability, mechanical properties and corrosion resistance of Cu-Zr-Ti-Ni-Nb bulk glassy alloys

Bulk glassy alloys exhibiting high strength and good corrosion resistance were formed in (Cu_0.6Zr_0.3Ti_0.1)_100-x-y Ni_yNb_x systems. The bulk glassy alloy rods with a diameter of 3 mm are formed in a wide composition range of 0 to 6 at%Ni and 0 to 6 at%Nb by copper mold casting. As the Nb content increases, the glass transition temperature (T_g) increases while the crystallization temperature (T_x) decreases, resulting in a decrease in ΔT_x (= T_x - T_g) from 60 K at 0 at%Nb to 36 K at 5 at%Nb. The high fracture strength (σ_c,f) exceeding 2000 MPa is obtained for the Cu-Zr-Ti-Ni-Nb alloys containing more than 3 at%Nb and their high strength alloys also exhibit distinct plastic elongation of 0.2 to 0.8%. The corrosion resistance of the Cu-Zr-Ti bulk glassy alloy is also significantly improved by the simultaneous addition of Ni and Nb and no loss in sample weight in 1 N HCl and 3%NaCl solutions is detected for the Cu-Zr-Ti-Ni-Nb alloys containing 5 at%Ni and 6 at%Nb or 2 at%Nb, respectively. The usefulness of the simultaneous addition of Ni and Nb on the σ_c,f and corrosion loss in conjunction with high glass-forming ability seems to affect significant influence on the future development of bulk glassy alloys with special functional characteristics.