Structure and magnetic properties of SmxCo72−xFe16Zr7B4Cu1 (x = 8, 12, 15) alloys

• We prepared SmxCo72−xFe16Zr7B4Cu1(x = 8, 12, 15) as-cast alloys and ribbons.
• We studied the effects of Sm content and cooling rate on structure and properties.
• The coercivity of x = 12 ribbons melt-spun at 40 m/s reaches up to ∼20 kOe.
• The high coercivity is related to a novel composite microstructure.
• In the microstructure, nanocrystalline clusters are embedded in amorphous matrix.

SmxCo72−xFe16Zr7B4Cu1 (x = 8, 12, 15) alloys with low level of Sm and mixed addition of several elements (Fe, Zr, B, Cu) were prepared via arc melting and rapid quenching technique. The influences of Sm content and cooling rate on the microstructure and magnetic properties of alloys were investigated. The ribbons melt-spun at 40 m/s present a novel composite microstructure with nanocrystalline phases embedded in amorphous matrix. Such a unique structure endows the x = 12 ribbons a coercivity as high as ∼20,000 Oe. Ferromagnetism of the amorphous matrix, the pinning effect of amorphous phase during the movement of domain-walls and exchange interactions among adjacent grains may contribute to the high coercivity performance.

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