The Influence of Cu Powders Doping on Magnetic and Mechanical Properties of Sm2Co17 Permanent Magnets

In this work, the influence of Cu powders doping on the magnetic and mechanical properties of Sm 2 Co 17 permanent magnets is systematically investigated. For high-energy-product Sm 2 Co 17 (low initial Cu content), the intrinsic coercivity is significantly improved from 11.7 kOe to 25.7 kOe with 1 wt.% Cu powders doping. The flux loss (soaking at 300 °C for 2 h) is reduced from 7.4% to 3.8%, and the average flexure strength is improved from 60.2 MPa to 74.1 MPa. As for high-temperature-resistant Sm 2 Co 17 (high initial Cu content), the intrinsic coercivity is slightly reduced from 39.2 kOe to 38.3 kOe with 1 wt.% Cu powders doping. The flux loss (soaking at 300 °C for 2 h) is increased from 1.4% to 3.4%, and the average flexure strength is improved from 86.7 MPa to 93.2 MPa. The differences in magnetic properties change of these two Sm 2 Co 17 permanent magnets are closely related with their initial Cu content. The doped Cu is prone to diffuse into intragranular cell boundaries in magnet with low initial Cu content. The increased Cu content in intragranular cell boundaries benefits the improvement of intrinsic coercivity, thus enhancing the thermal stability and reducing the flux loss. Doping Cu powders may increase the Cu-rich phase around ground boundaries, which will hinder the grain growth during heat treatment. The decrease of grain size will enhance the flexure strength, while it will increase the flux loss.