MAGNETIC PROPERTIES AND CRYSTAL STRUCTURES OF Nd-Fe-Co-B SYSTEM PERMANENT MAGNETS.

The authors report on the effects of partial substitution of cobalt for iron in the Nd-Fe-B system. The samples prepared by powder metallurgical methods were of the composition Nd//2 //3 // minus //y Fe//7 //7 // minus //2 //x Co//2 //x B//y , where x equals 0 to 10 and y equals 5 to 10. Significant improvement in the Curie temperature has been obtained by increasing the cobalt content in the alloy system. The temperature coefficient sigma r of the Nd//1 //6 Fe//6 //6 Co//1 //1 B//7 is about -0. 02%/ degree C in the temperature range 20 to 100 degree C, compared with -0. 03%/ degree C for Nd-Fe-B samples. A magnet was developed in the Nd-Fe-Co-B system with a maximum energy product of 41 MGOe.