Glass-forming ability and magnetic properties of mechanically solid-state reacted Co 100− xTi x alloy powders

Abstract

A high-energy ball milling technique using the mechanical alloying method has been employed for fabrication of glassy Co 100− x Ti x (25≤ x≤67) alloy powders at room temperature. The fabricated glassy alloys in the Co-rich (33≥ x) side exhibit good soft magnetic properties. The binary glassy alloys for which the glass transition temperatures ( T g) have rather high temperatures (above 800 K), show large supercooled liquid regions before crystallization (Δ T x larger than 50 K). The reduced glass transition temperature (ratio between T g and liquidus temperatures, T l ( T g/ T l)) was found to be larger than 0.56. We have also performed post-annealing experiments on the mechanically deformed Co/Ti multilayered composite powders. The results show that annealing of the powders at 710 K leads to the formation of a glassy phase (thermally enhanced glass formation reaction), of which the heat of formation was measured directly. The similarity in the crystallization and magnetization behaviors between the two classes of as-annealed and as-mechanically alloyed glassy powders implies the formation of the same glass state.