Structure and magnetic properties of (Sm,Y)Fe_7N_δ/α-Fe nanocomposited magnets

摘要

The structure and magnetic properties of Sm_(7-x)Y_xFe_(93)(0 ≤ x ≤ 2) alloys prepared by mechanical alloying, heat treatment and nitrogenation have been studied by means of X-ray diffraction, pulsed magnetometer, a.c. initial susceptibility. After annealed at 580℃ for 30 min and nitrided at 450℃ for 3 h, the alloys consist of an isotropic mixture of two phases of α-Fe and (Sm,Y)Fe_7N_δ-type. Due to the exchange coupling between the magnetic nanograins, the remanence enhancement is obviously observed. The hard magnetic phase is (Sm,Y)Fe_7N_δ phase in all the nitrided alloys. With increasing the Y content, the coercivity monotonously decreases and the remanence increases, while the Curie temperatures of hard magnetic phase vary slightly.