Study On The Fabrication, Microstructure And Magnetic Properties Of Sm₃(Fe,Ti)₂₉N_x/α-Fe Dual-Coupling Nanocomposite Permanent Magnets

Sm3(Fe,Ti)29Nx/a-Fe dual-coupling nanocomposite permanent magnets have excellent magnetic properties due to the dual-coupling effects between the soft magnetic phase a-Fe which provides high saturation magnetization and the hard magnetic phase Sm3(Fe,Ti)29Nx which offers high coercivity, moreover the existence of soft magnetic phase a-Fe largely decreases the content of rare earth and the cost. So the study has the most potential for the application of magnets. In this paper, Sm3(Fe,Ti)29Nx and a-Fe dual-coupling nanocomposite magnets have been successfully fabricated with the addition of stable element Ti and with the help of the melt-spun, crystallization and nitrogenation techniques. And the techniques of crystallization and nitrogenation, the microstructure and the magnetic properties have also been studied in detail. For Sm10Fe84Ti6 and Sm10Fe84Ti5Cu1, both the cast and annealed alloys are composed of four kinds of phases such as a-Fe, Sm3(Fe,Ti)29, little amount of Sm2(Fe,Ti)17 and SmFe2, but the contents of a-Fe and SmFe2 decrease and the contents of Sm3(Fe,Ti)29 and Sm2(Fe,Ti)17 increase after annealing compared with the cast alloys. Only Sm3(Fe,Ti)29 and a-Fe exist in the melt-spun alloys, and Sm3(Fe,Ti)29 phase is a little amorphous. For Sm10Fe84T16 and annealed Sm10Fe84Ti6 alloys, when crystallized at 700℃ some fine grains are separated hy amorphous phase, and when crystallized at 750 ℃ for30min the ribbon is totally crystallized from which the tight binding between grains and straight smooth interface with fine grains less than 50nm can be observed by TEM. However different grains are disorderly distributed in the ribbons of Cu-added alloys with fine grains precipitated along the coarse interface. Only Sm3(Fe,Ti)29Nx and a-Fe exist in the four kinds of nitrogenated alloys. And all of the coercivity and remnant magnetism reach the maximum when crystallization at 750℃. The magnetic properties of the alloy without the addition of Cu are better than those of the alloy with the addition of Cu. The maximum coercivity of Sm10Fe84Ti6 is 1778.4 Oe when measured in the field of 15000Oe. The hysteresis loop is smooth and full for the alloy without the addition of Cu which means good dual-coupling exists between Sm3(Fe,Ti)29Nx and a-Fe nano-grains.