Preparation of Anisotropic NdFeB Powders by Crushing Sintered Magnet at High Temperatures (Ⅰ)
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摘要: 為了使用NdFeB燒結磁體制取各向異性的高性能磁粉,研究了在較高溫度下NdFeB燒結磁體機械破碎時的斷裂行為.結果表明:破碎溫度升至600%以上時,由于共晶反應形成少量的液態晶界相而使燒結磁體明顯易于破碎,其主要斷裂方式由室溫下的穿晶斷裂轉變成高溫下的沿晶斷裂.高溫破碎的磁粉中,富釹相的X射線衍射峰強度明顯高于室溫下破碎磁粉的衍射峰.Abstract: In order to manufacture anisotropic magnet powders from sintered NdFeB magnet, the fracture behavior of sintered NdFeB magnet in the mechanical crush process at high temperatures was studied. The experimental results show that the sintered NdFeB magnet can be crushed to fine powders much more easily than that at room temperature as the crushing temperature is raised to above 600℃, which results from eutectic formation of the minor liquid phase at the grain boundary area. The morphology of the crushed powders exhibits that the fracture at temperatures higher than the eutectic temperature tends to be intergranular instead of transgranular which occurs at lower temperatures. Through X-ray diffraction analysis the magnetic powders obtained by a crush process at higher temperatures shows much higher diffraction peaks of the Nd-rich phase.
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Key words:
- sintered magnet /
- magnet powders /
- fracture
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