LOW RARE-EARTH ND-FE-B BONDED MAGNETS WITH IMPROVED IRREVERSIBLE FLUXLOSS

The effects of Nb addition on magnetic properties and irreversible flu x loss were studied on bonded magnets with compositions of Nd8Fe86-xB6 Nbx, where x=0-3. An irreversible flux loss was measured at P-c = 2 af ter exposure at 393 K for 3.6 ks in air. It was found that the Nc addi tion of 2 at. % or more decreased the irreversible flux loss. The valu e was less than 5%, similar to that obtained with MQP-B magnets. B-r d ecreased with the increase in Nb content. The effect of Nd content on the magnetic properties and irreversible flux loss was also studied on the bonded magnets with compositions of NdxFe92-xB6Nb2, where x = 6-8 . The bonded magnet with the optimum composition of Nd6.5Fe85.5B6Nb2 h ad B-r similar to that of MQP-Q magnets that did not contain Nb, and t he value of irreversible flux loss was comparable to that of MQP-B mag nets. A multipole magnetizability test on the bonded magnets with the above optimum composition was carried out, and the total flux of the b onded magnets was about 10% higher than that of MQP-B magnets for the 23 mm outside diameter magnet with 48 poles. (C) 1997 American Institu te of Physics.