Ununiformity of Magnetic Properties for Melt-Spun NdFeB Powder

Abstract:

Superior and inferior magnetic powders can be separated from the same batch crystallined NdFeB magnetic powders containing Zr and Co elements by magnetic separation method due to their magnetic ununiformity. The compositions and microstructures of the two powders with different magnetic properties were investigated. The results show that the superior powders contain less Zr and a relative more Fe, with integrated grains of about 20～60 nm in size and clear grain boundary without other phases. And the inferior powders contain more Zr and a relative lower Fe and metastable microstructures including the amorphous phases, the α-Fe and amorphous phases, and the un-integrated Nd2Fe14B phases of ≤10 nm in size. It is presumed that the ununiform magnetic properties are due to the elevated crystallization temperature induced by the more Zr content for the inferior powders