Table of Contents
Physics Research International
Volume 2012, Article ID 416717, 4 pages
http://dx.doi.org/10.1155/2012/416717
Research Article

Improvement of Thermal Stability of Nd-Tb-Fe-Co-B Sintered Magnets by Additions of Pr, Ho, Al, and Cu

1Research and production Company “Magnets and Magnetic Systems” Ltd., 127238 Moscow, Russia
2Department of Physics, Moscow State University, 117234 Moscow, Russia
3Institute for Energy Technology, Kjeller and University of Oslo, 2027 Kjeller, Norway

Received 29 July 2011; Revised 26 January 2012; Accepted 29 January 2012

Academic Editor: Arcady Zhukov

Copyright © 2012 A. A. Lukin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The present work investigates the influence of Pr, Al, Cu, B and Ho which were introduced into the Co-containing sintered magnets of Nd-Dy-Tb-Fe-Co-B type on the magnetic parameters ( , , , ). The effect of heat treatment parameters on magnetic properties was also studied. It was revealed that the essential alloying of NdFeB magnets by such elements as Dy, Tb, Ho, Co as well as by boron-forming elements, for example, by titanium, may lead to reducing of F-phase quantity, and, as a consequence, to decreasing of magnetic parameters. It was also shown that additional doping of such alloys by Pr, B, Al and Cu leads to a significant increase of the quantity of F-phase in magnets as well as solubility of the Dy, Tb, Ho and Co in it. This promotes the increase of magnetic parameters. It was possible to attain the following properties for the magnets (Nd0,15Pr0,35Tb0,25Ho0,25)15(Fe0,71Co0,29)bal · Al0,9Cu0,1B8,5 (at. %) after optimal thermal treatment {1175 K (3,6–7,2 ks) with slow (12–16 ks) cooling to 675 K and subsequently remaining at  K for 3,6 ks—hardening}:  T,  kA/m,  kJ/m3, %/K in the temperature interval 223–323 K.