Magnetic properties of Sm–Fe–Ti nanocomposite magnets with a ThMn12 structure

Sm–Fe–Ti alloys were produced by melt-spinning followed by heat treatment. The rapidly solidified melt-spun ribbons did not contain any hard magnetic ThMn12 phase and thus showed low coercivity. Although no hard magnetic ThMn12 phase was obtained by annealing SmFe12 melt-spun ribbon, annealed SmFe11.5Ti0.5 and SmFe11Ti melt-spun ribbons contained some hard magnetic ThMn12 phase and exhibited high coercivity. The highest coercivity of 0.4 MA/m with a remanence of 63.5 A m2/kg was achieved in the annealed SmFe11Ti melt-spun ribbon with the soft magnetic α-Fe and hard magnetic ThMn12 phases. The origin of the high coercivity in the annealed SmFe11Ti melt-spun ribbon was found to be the nanosized grains of the α-Fe and ThMn12 phases.

► Sm–Fe–Ti nanocomposite magnet with ThMn12 phase was successfully produced melt-spinning followed by heat treatment.
► The highest coercivity of 0.4 MA/m with a remanence of 63.5 A m2/kg was achieved in the annealed SmFe11Ti melt-spun ribbon.
► The origin of the high coercivity in the annealed SmFe11Ti melt-spun ribbon was found to be the nanosized grains of the α-Fe and ThMn12 phases by TEM studies.