IMPROVEMENTS OF MAGNETIC-PROPERTIES OF SM2FE17CX MELT-SPUN RIBBONS BY ADDITIONAL ELEMENTS

Before melt-spinning of the alloys, the formation of a Sm2Fe17 phase with Th2Zn17 type structure in Sm2(Fe0.9Cr0.1)17C1.6 alloys is confirmed by studying the microstructure of ingots. Sm2(Fe0.9Cr0.1)17C1.6 melt-spun ribbon exhibits the coercive force of 672 kAm-1 (8.4 kOe) after annealing at 750-degrees-C for 30 min. Microstructural studies indicate that the ribbon consists of fine grains of 50-150 nm in diameter. It is found that a phase transformation from TbCu7 to Th2Zn17 is caused with increasing annealing temperature, by X-ray analysis and the variation of magnetic hysteresis loops. The Ga containing ribbon of Sm2(Fe0.9Ga0.1)17C1.6 exhibits the coercivity of 680 kAm-1 (8.5 kOe) after annealing. A further addition of M (M = Co, Mn) to Sm2(Fe, Cr)17C1.6 and Sm2(Fe, Ga)17C1.6 alloys improves the magnetic properties. Especially, Sm2(Fe0.85Ga0.1Co0.05)17C1.6 ribbon annealed at 650-degrees-C for 30 min exhibits high coercivity of 1008 kAm-1 (12.6 kOe) with the (BH)max of 62.4 kJm-3 (7.8 MGOe). This is the highest magnetic properties among the reported values of Sm2Fe17Cx melt-spun ribbons so far.