Fabrication and characterizations of new glassy CO71Ti24B5 alloy powders and subsequent hot pressing into a fully dense bulk

A single Glassy phase of Co71Ti24B5 alloy has been synthesized by high-energy ball milling the elemental powders at room temperature, using the mechanical alloying method. The synthetic glassy powder obtained after 130 ks of ball milling exhibits good soft magnetic properties with a polarization magnetization and coercivity values of 1.01 T and 2.86 kA/m, respectively. This ternary glassy alloy in which its glass transition temperature (T-g) lies at a rather high temperature (805 K) crystallizes at 868 K through a single sharp exothermic peak with an enthalpy change of crystallization (DeltaH(x) of -3.28 kJ/mol. The supercooled liquid region before crystallization, DeltaT(x) of the synthesized glassy powders shows a large value (63 K) for a ternary system. The reduced glass transition temperature (ratio between T-g and liquidus temperatures, T-1 (TgIT1)) was found to be 0.55. The end product of the glassy powder (130 ks) was compacted in an argon gas atmosphere at 835 K with a pressure of 780 MPa, using the hot-pressing technique. The consolidated sample is fully dense (similar to99.5 pct) and maintains its chemically homogeneous glassy structure. The measured polarization magnetization and coercivity values of as-consolidated powders are measured and found to be 0.96 T and 2.92 kA/m, respectively. The Vickers microhardness of the bulk glassy Co71Ti24B5 sample is measured and found to be in the range between 7.32 and 7.46 GPa.