Magnetization reversal of Ti-modified Nd2 Fe14 B/α-Fe nano composite magnets

Ti-modified Nd2 Fe14 B/ α-Fe magnets were prepared by a single-roller melt spinning technique. Nano structured Nd2 Fe14 B and α-Fe particles subsequently crystallized from the amorphous matrix after an annealing process. The best magnetic properties were obtained from the Nd10 Fe83 B6 T1 flakes as follows: Hc= 11.1 k O e, Br=9.7 kG, and (B H)max=15.9 MGO e. The remanence ratio of 0.85, which is much higher than the theoretical value of 0.5 for the isolated-particle system, indicates a strong exchange coupling between neighboring particles. The effect of exchange interaction was investigated from Henkel plots. The DCD and IRM data depict that the variation in irreversible magnetization is responsible by the hard magnetic phase. Meanwhile, the reversible magnetization becomes dominating as the amount of the soft magnetic phases increased. The nucleation field of the magnetization reversal process was observed to increase with the decreasing amount of α-Fe. The composition of the Ti-modified magnets plays an important role in determining the microstructure, thus influence magnetization reversal processes. (author)