Sm(Co, Fe, Cu, Zr)z sintered magnets with a maximum operating temperature of 500 °C

The Fe content v dependence of magnetic properties of Sm(CobalFevCu0.088Zr0.025)(7.5) (v = 0-0.30) sintered magnets has been systematically studied. With increasing v, the remanences B-r and the maximum energy products (BH)(max) at room temperature increase initially and reach an optimal B-r of 1.055 T for v = 0.27 and an optimal (BH)(max) of 205 kJ/m(3) for v = 0.21, and then decrease sharply. Fe content significantly affects the temperature coefficient of intrinsic coercivity. The lower the Fe content is, the smaller the temperature coefficient of coercivity is. A temperature coefficient of intrinsic coercivity of -0.14%/ degrees C (20-500 degrees C) has been achieved for v = 0.07, as compared with -0.23%/degrees C for v = 0.21. A high temperature sintered magnet with a maximum operating temperature of 500 degrees C has been obtained on the composition of Sm(CobalFe0.07Cu0.088Zr0.025)(7.5). The initial magnetization curve exhibits that this high temperature magnet is still controlled by a strong domain wall pinning mechanism up to 500 degrees C. (C) 2006 Elsevier B. V. All rights reserved.