Corrosion Resistance and Coercivity of NdFeB Sintered Magnets with Different Doped Elements

NdFeB sintered magnets doped with six different elements were synthesized for investigating the doping effects both on the corrosion resistance and magnetic properties. Polarization curves and SEM indicated doping element with the more higher standard eletrode potentials comparing with that of Nd could not definitely improve the corrosion resistance. Furthermore, it could be proved the smaller volume fractions of Nd-rich phase, homogeneous crystal grain size and Nd-rich distribution were good for improving corrosion resistance. Combining with demagnetization curves, it could be concluded that Tb doped sample not only showed the best corrosion resistance with the lowest corrosion current density icon of 6.399 mu A.cm(-2), but also performed the highest coercivity of about 2303 kA.km(-1). The result of Kronmuller-Plot curves indicated the micromagnetic parameter alpha(k) played a part in enhancing coercivity while the decrease of N-eff played a more important part in coercivity diminution.