Thermal stability and saturation magnetization of a new series of amorphous Fe 80− xCo xP 14B 6 (20≤ x≤40) alloys

Abstract

A series of new Fe 80− x Co x P 14B 6 ( x=20, 25, 30, 32, 35, 40) glasses has been prepared by melt-spinning technique. The FeCo-based glasses crystallize via one stage eutectic reaction into a mixture of a-Fe (bcc) solid solution and a b.c.-tetragonal Fe 3P-like phase at temperatures approx. 50 K higher than the Fe 80− x Ni x P 14B 6 metallic glasses. The compositional dependence of the crystallization temperatures at constant rate heating of the FeCo-based glasses has a minimum at x=30 that correlates well with the values of the apparent activation energy of crystallization derived from the Kissinger analysis. The as-quenched Fe 80− x Co x P 14B 6 ribbons within the range examined have superior saturation magnetization in comparison with that of the commercial Fe 40Ni 40P 14B 6 glass, for example the maximum value of the saturation magnetization M s estimated from vibrating sample magnetometer measurements is as high as 153 emu/g (about 1.415 T, for a density of 7.42 g/cm 3) for the Fe 48Co 32P 14B 6 alloy.