Improvement of Corrosion Resistance of Sintered NdFeB Magnets by Intergranular Addition of AlN Nanopowders

Abstract:

AlN nanopowders were added into Nd28Dy2.4FebalB0.98Al0.1Ga0.1Nb0.1 sintered magnets as grain boundary modifiers with the aim of improving the corrosion resistance and magnetic properties of the magnets. It is found that the appropriate intergranular addition of AlN nanopowders can improve the corrosion resistance. Optimum corrosion resistance can be obtained when 0.1% (mass fraction) AlN is added. In addition, the intrinsic coercivity (Hcj) is improved greatly by the AlN addition. Microstructure observation indicates that as AlN nanopowders are added to the intergranular phase, the grains are refined effectively. As a result, both the intrinsic coercivity and corrosion resistance are increased simultaneously