Effect of annealing process on magnetic properties of Sm(Co0.6Fe0.27Cu0.1Zr0.03)7.5 ribbons

Sm(Co0.6Fe0.27Cu0.1Zr0.03)7.5 ribbons were prepared by melt-spun method. The results showed that the remnant magnetization Mr and intrinsic coercivity Hci had a rapid increase when the heating rate increased from 5 to 10 °C/min. But the increase of Mr and Hci were observed to be very little when the heating rate was further increased to 20 °C/min. 10 °C/min was the critical heating rate for obtaining high magnetic properties. The maximum values of Mr and Hci reached 0.70 T and 780.1 kA/m when the annealing temperature and annealing time were optimized to be 800 °C and 1 h, respectively. Proper second-step heat treatment could suppress the decrease of Hci when the cooling rate increased from 0.7 to 5 °C/min, which could reduce the cooling time effectively.