The effect of the HDDR process on the production of Pr-Fe-Co-B-Nb sintered magnets

Abstract

Sintered magnets have been produced with powder obtained with the HDDR process. This new processing procedure for the production of the sintered magnets has been adopted in an attempt to reduce the milling time. Annealed ingot alloys based on the compositions Pr14Fe75.9CoxB6Nb0.1 (x= 0; 4; 8; 10; 12; 16) have been employed in this investigation. A high rare earth content copper-containing alloy, Pr20.5FebalB5Cu2.0, was used as a sintering aid. A mixture of the HDDR powder obtained from these alloys was used to prepare sintered magnets. Standard hydrogen decrepitation (HD) magnets have also been included in this work for a comparison. A remanence of 1173 mT was achieved with the alloy Pr14Fe67.9Co16B6Nb0.1 processed using the HDDR process and a milling time of only 5 h. The microstructures of the magnets have been investigated by scanning electron microscopy and energy dispersive X-ray analysis.