Phases and magnetic properties of the devitrified metallic glasses Co 66Cr 14B 20 and Fe 43Cr 25Ni 20B 12

Abstract

Devitrification of amorphous melt-spun ribbons with compositions of Co 66Cr 14B 20 and Fe 43Cr 25Ni 20B 12 was investigated as a method of making fine dispersions of magnetic phases within a non-magnetic matrix. Such a process may ultimately be applied to amorphous films to produce solid-state dispersions of particles that possess magnetic properties suitable for magnetic recording purposes. The ribbons were isochronally annealed so as the cause a large number of magnetic particles to precipitate out of a glassy matrix. The Co-based ribbons devitrified to form a series of Cr-borides and cubic (CoCr) 23B 6. The coercivity and saturation magnetization varied systematically with heat-treatment temperature, both reaching their maximum values of 530 Oe and approximately 300 G for T A = 610 °C. The Fe-based ribbons first devitrified to form ferromagnetic α-iron which transformed to paramagnetic Ni-rich Austenite upon annealing at higher temperatures. The annealed Fe-based ribbons displayed a maximum specific magnetization of approximately 400 G and a maximum coercivity of 424 Oe. However, these two properties are not maximized at the same temperature.