Nd_2Fe_(17) nanograins effect on the coercivity of HDDR NdFeB magnets with low boron content

摘要

Relationships between the coercivity of hydrogenation disproportionation desorption recombination (HDDR) Nd_(12.5)Fe_(81.5-x)Co_6B_x bonded magnets and boron content were investigated. Nd_2Fe_(17) phase with planar magnetic anisotropy is present in the microstructure when x= 4at%-5.88at%, which does not reduce the coercivity of the bonded magnets. High-resolution transmission electron microscopy (TEM) images show that Nd_2Fe_(17)phase exists in the form of nanocrystals in the Nd_2Fe_(17) matrix. There is an exchange-coupling interaction between the two phases so that the coercivity of HDDR Nd_(12.5)Fe_(81.5-x)Co_6B_x bonded magnets is hardly reduced with a decrease in boron content.