Crystallization and magnetic properties of amorphous NdxB19-xFe81 (0⩽x⩽19) alloys

Abstract Crystallization and its influence on magnetic and structural properties of rapidly quenched amorphous Nd x B 19-x Fe 81 (0⩽x⩽19) alloys have been investigated. Electrical resistivity measurements were made to determine the crystallization temperature, which was found to increase from 435°C for x=0 to 636 °C for x=6. The crystalline phase after various heat treatments were identified by X-ray analysis. The annealing temperature dependence and the composition dependence of phase components in the annealed samples were discussed together with the correlation between magnetic properties and the structure. The as-quenched samples are X-ray-amorphous with a coercivity below 800 A/m. After annealing the hard magnetic states occur in the samples for 8⩽x⩽15. The coercivity increases with increasing annealing temperature to a maximum and then decreases. It is noticeable that when the Nd concentration is only x=3, H c as high as 168 kA/m was obtained by annealing at about 660 °C while the X-ray data shows the presence of α-Fe and Fe 3 B only.