Formation and mechanical properties of bulk glassy Ni57-xTi23Zr15Si5Pdx alloys

The glass-forming ability in Ni57_xTi23Zr15Si5Pdx (x = 0, 5, 10, 12.5, 15 a nd 20) alloys as a function of Pd concentration was examined by melt-spinni ng and copper mold casting methods. All the melt-spun ribbons are in a glas sy state, DeltaT(x)(DeltaT(x) = T-x - T-g) and T-g/T-m were used to evaluat e the glass-forming ability, where T-g, T-x and T-m represent the glass tra nsition, crystallization and melting temperatures, respectively. The observ ation of large DeltaT(x) and T-g/T-m values in the 12.5 at%Pd alloy implies a high glass-forming ability. At this composition, a cylindrical bulk allo y with a diameter of 2 mm was verified to be in a single glassy state. For the bulk cylinder of 3mm in diameter, the volume fraction of glassy phase i s approximately 92%. The compression fracture strength (sigma) and Vickers hardness: (H-v) of the bulk glassy alloy are 2100 MPa and 620, respectively . These results demonstrate the good mechanical performance of the present Ni-based bulk glassy alloy, which is prominent for future application.