Effects of titanium and zirconium addition on magnetic properties of Sm2Fe17 melt-spun ribbons

The structures and magnetic properties of Sm2(Fe,Co)17 melt-spun ribbons with Ti and Zr added in the ratios of (Sm1-xZrx)2(Fe0.7Co0.3)17-yTiy (x=0–0.3, y=0–2.0) were investigated. The (Sm1-xZrx)2(Fe0.7Co0.3)17-yTiy (x=0–0.3, y=0–2.0) melt-spun ribbons showed low coercivity, but after annealing their coercivity differed according to the amounts of Zr and Ti contained. Structural studies revealed that the addition of Ti and Zr to the Sm2(Fe,Co)17 alloys resulted in a change from the Th2Zn17-type phase to the ThMn12-type phase. It was found that the specimens with a low coercivity retained the Th2Zn17-type phase (an average diameter of 100 nm), whereas the specimens with a high coercivity mainly consisted of the ThMn12-type phase (an average diameter of 30 nm). Among the specimens tested, (Sm0.7Zr0.3)2(Fe0.7Co0.3)15.5Ti1.5 melt-spun ribbon with the ThMn12-type phase exhibited a high coercivity of 4.0 kOe.