Effects of thermal annealing on improved magnetic properties and microstructure for SmFe11Ti alloy

Abstract SmFe11Ti alloys with ThMn12 structure are prepared by arc melting followed by melt spinning. Effects of thermal annealing on the phase constituent, microstructure and magnetic properties are investigated in details. Before and after annealing, the phase constituent of alloys remains unchanged, containing 1:12 main phase, α-Fe phase, Fe2Ti phase as well as amorphous phase. Under thermal annealing condition of 800 oC/30 min, the highest remanence and coercivity, as high as 0.63 T and 380 kA/m, are obtained, respectively. The improvement of coercivity may be attributed to decreased defects and improved inhomogeneity of main phase composition, while enhanced remanence ascribes to the strong exchange coupling effect. In addition, the temperature coefficient of coercivity of -0.42 %/K is determined, showing excellent thermal stability.