高温破碎烧结磁体制取各向异性NdFeB磁粉(Ⅰ)

Preparation of Anisotropic NdFeB Powders by Crushing Sintered Magnet at High Temperatures (I)

为了使用NdFeB烧结磁体制取各向异性的高性能磁粉,研究了在较高温度下NdFeB烧结磁体机械破碎时的断裂行为.结果表明:破碎温度升至600％以上时,由于共晶反应形成少量的液态晶界相而使烧结磁体明显易于破碎,其主要断裂方式由室温下的穿晶断裂转变成高温下的沿晶断裂.高温破碎的磁粉中,富钕相的X射线衍射峰强度明显高于室温下破碎磁粉的衍射峰.

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.