Improving permanent magnetic properties of rapidly solidified nanophase RE-TM-B alloys by compositional modification

Rapid solidification is one of the most important techniques to produce nanocrystalline rare-earth-transition metal-boron (RE-TM-B) hard magnetic materials. To achieve high performance on these NdFeB-based alloys, compositional modification and microstructure optimization have been frequently employed. In this short review, various substitutions and doping elements have been discussed regarding to their behaviors in adjusting the individual or combined hard magnetic properties as well as the microstructure based on our recent results. It has been demonstrated that Pr and Dy enhance coercivity H-j(C), whereas Sm reduces H-j(C) due to their effects on intrinsic properties. Co improves the thermal stability as well as the microstructure. Introducing Fe65Co35 is a possible approach to enhance the magnetization and maximum energy product (BH)(max). As a doping element, Ta was found to play an important role to obtain an appropriate combination of magnetic properties for this type of alloys. (C) 2009 Elsevier B.V. All rights reserved.