Preparation and characterization of quaternary magnetic Fe80-xCoxP14B6 bulk metallic glasses

A new series of quaternary magnetic Fe80-xCoxP14B6 (x = 20, 30, 40, 50, 60 at. %) bulk metallic glasses (BMGs) has been prepared by combining fluxing treatment and J-quenching technique, and the maximum critical diameter for fully glass formation reaches up to 2.0 mm for x = 40 among this series of FeCo-based BMGs. The effects of Co content on glass-forming ability, thermal stability, mechanical and magnetic properties of the present FeCo-based BMGs have been systematically investigated. It is found that the highest thermal stability, namely the highest glass transition temperature (Tg) and the onset crystallization temperature (Tx), is achieved when the ratio of Fe and Co contents is 1:1 in the present FeCo-based BMGs. It should be noted that the maximum Curie temperature reaches 791 K when x = 40, which is the highest Curie temperature for (Fe, Co, Ni)-based BMGs so far as is known. Moreover, the present FeCo-based BMGs exhibit very good soft magnetic properties and large room plasticity, which are prom...