Structure and Magnetic Properties of Heat-Resistant Sm(Co0.796−xFe0.177CuxZr0.027)6.63 Permanent Magnets with High Coercivity
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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°C and exists in the entire temperature range from 850°C to 400°C. The Curie temperature of the R2:17 and 1:5 phases is approximately 815°C and 580°C, respectively. The magnets have the following hysteresis properties at room temperature: Br = 890–920 mT, JHc = 2.4–2.6 MA/m, BHc = 629–676 kA/m, and (BH)m = 143–159 kJ/m3. In the temperature range of 20–500°C, the temperature coefficients of Br and JHc of the magnets (x = 0.117 and 0.130) do not exceed |− 0.070| and |− 0.172|%/°C, respectively.
This work was supported by the Russian Foundation for Basic Research (Grant No. 17-52-80072) and DST-BRICS and the state assignment of FASO of Russia (topic “Magnet” no. AAAA-A18-118020290129-5). The x-ray diffraction investigation and magnetic measurements were performed at the Center of Collaborative Access of IMP UB RAS. The funding was provided by Department of Science and Technology, Ministry of Science and Technology (Grant No. 258).
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