Magnetic properties, phase evolution, and microstructure of melt spun Sm(Co,M)xCy (M=Hf and Zr; x=5–9; y=–0.15) ribbons

Magnetic properties, phase evolution, and microstructure of melt spun Sm(Co0.97M0.03)xCy (M=Hf and Zr; x=5–9; y=0–0.15) ribbons quenched at the wheel speed of 40 m/s have been investigated. X-ray diffraction analysis show that the main phases exist in Sm(Co0.97M0.03)x ribbons are 1:5 for x=5 and 5.5, 1:5 and 1:7 for x=6 and 6.5, 1:7 for x=7 and 7.5, 1:7 and 2:17 for x=8, and 2:17 for x=8.5 and 9. The grain size of 200–500 nm for these two series of ribbons is almost unchanged when x is increased from 5 to 9. Accordingly, the magnetic properties of Sm(Co0.97M0.03)x ribbons (M=Hf and Zr) are mainly dominated by their phase constitutions. Furthermore, a slight addition of C to Sm(Co0.97M0.03)x ribbons refines the grain size down to 10–50 nm, resulting in the improvement of magnetic properties. Sm(Co0.97Hf0.03)7.5C0.1 ribbons show the optimal magnetic properties of Br=6.9 kG, Hic=9.2 kOe, and (BH)max=10.0 MGOe. For the Sm-lean Sm(Co,Hf)xCy (x=8.5–9) ribbons, higher Hf and C content are required to improve the magnetic properties. The magnetic properties of Br=6.8 kG, Hic=6.2 kOe, and (BH)max=7.2 MGOe could be obtained in Sm(Co0.94Hf0.06)9C0.15 ribbons.