Structure and Magnetic Properties of Heat-Resistant Sm(Co0.796-xFe0.177CuxZr0.027)(6.63) Permanent Magnets with High Coercivity

摘要

The structure and temperature stability of high-temperature permanent magnets Sm(Co0.796-xFe0.177CuxZr0.027)(6.63) (x=0.117 and 0.130) were studied using x-ray diffraction analysis, thermomagnetic analysis, and scanning and transmission electron microscopy. The magnets have a nanocrystalline cellular structure composed of the R2:17 cell phase, 1:5 boundary phase (27-28% by volume), and Z-phase platelets. The 1:5 phase is formed in the course of isothermal annealing at 850 degrees C and exists in the entire temperature range from 850 degrees C to 400 degrees C. The Curie temperature of the R2:17 and 1:5 phases is approximately 815 degrees C and 580 degrees C, respectively. The magnets have the following hysteresis properties at room temperature: B-r=890-920mT, H-J(c)=2.4-2.6MA/m, H-B(c)=629-676kA/m, and (BH)(m)=143-159kJ/m(3). In the temperature range of 20-500 degrees C, the temperature coefficients of B-r and H-J(c) of the magnets (x=0.117 and 0.130) do not exceed |-0.070| and |-0.172|%/degrees C, respectively.