Influence of Fe Substitution for Co on the Magnetic Properties of Melt-Spun CoFeZr Alloys

Abstract

Influence of Fe substitution for Co on the magnetic properties of melt-spun Co-Fe-Zr alloys are studied. The room-temperature coercive field Hc and energy product (BH)max of the melt-spun Co82−xFexZr18 alloys are found to increase with increasing the substrate velocity vs at vs ⩽ 47 m/s. The annealing temperature dependence of Hc and (BH)max show a wide maximum at about Ta = 650°C for x = 0 and Ta = 520°C for x = 8. The room-temperature magnetization σs measured in a field of 8 kOe for the Co82−xFexZr18 samples melt-spun with vs = 47 m/s increase with x from 59.9 e.m.u./g for x = 0 to 78.4 e.m.u./g for x = 10, but the coercive field decreases monotonically. The highest room-temperature coercive field Hc = 3.0 kOe and energy product (BH)max = 3.9 MGOe are obtained in optimal heat treated Co82Zr18 and melt-spun Co74Fe18Zr8 alloys, respectively. X-ray diffraction and thermomagnetic measurements on Co82−xFexZr18 show that the as-quenched sample and the sample annealed at Ta < 700°C exhibit a metastable (Co, Fe)5Zr phase coexisting with f.c.c. (Co, Fe). In the Co82−xFexZr18 alloys annealed at 950°C, the Fe atoms enter the Co lattice, forming (Co, Fe)5Zr, (Co, Fe)23Zr6, and f.c.c. (Co, Fe). The hard-magnetic properties of these materials are related to the presence of the 5: 1 phase. [Russian Text Ignored].