High temperature properties improvement and microstructure regulation of Sm2Co17-based permanent magnet

It is well known that the high temperature magnetic properties of traditional Sm2Co17-based magnets can be further improved through adjustment of chemical composition and technique process. The Hcj of Sm(CobalFe0.1Cu0.09Zr0.03)z (z=7.0-7.3) magnets fluctuate over a large range at the variation of Sm content, and Sm(CobalFe0.1Cu0.09Zr0.03)7.2 magnet shows excellent magnetic properties as (BH)max of 22.5 MGOe, Hcj of 28.3 kOe and Br of 9.65 kG at room temperature respectively. Meantime through optimization of solid solution conditions, the Sm(CobalFe0.1Cu0.09Zr0.03)7.2 magnets possess excellent magnetic properties as Br=7.22 kG, Hcj=7.6 kOe, (BH)max=11.6 MGOe at 500 °C. The β (temperature coefficient of coercivity from room temperature to 500°C) can be optimized to +0.1113%/°C from −0.134%/°C as quenching temperature increases from 420 °C to 830 °C, but Hcj deteriorates to 1.4 kOe from 28 kOe. Distribution of Cu content in cell boundaries for Sm(CobalFe0.1Cu0.09Zr0.03)7.2 quenched at 420 °C and 830 °C was analyzed using TEM-EDS, the result indicates that distribution of Cu is the main reason to give rise to the variation of Hcj and β.