Magnetic Properties and Crystal Structures of Nd-Fe-Co-B System Permanent Magnets

Abstract

Several experimental studies recently have been carried out on magnetic properties for Nd-Fe-B alloys. In this paper, we report on the effects of partial substitution of cobalt for iron in the Nd-Fe-B system. The samples prepared by powder metallurgical method have composition Nd_23-yFe_77-2xCo_2xB_y, where x=0∼10, y = 5∼10. we have obtained significant improvement in the Curie temperature with increasing cobalt content in the alloy system. The temperature coefficient of σr of the Nd₁₆Fe₆₆Co₁₁B₇ is about -0.02%/°C, in the temperature range 20∼100°C compared with -0.03%/°C for the Nd-Fe-B samples. We have achieved a magnt with the maximum energy product of 41 MGOe in the Nd-Fe-Co-B system.