PROPERTIES OF SINTERED AL SUBSTITUTED NDFEB MAGNETS

The effect of partial substitution of Fe by Al (Al, Al2O3) on the magnetic properties and the corrosion resistance of the sintered NdFeB magnet has been investigated. With the increasing amount of Al, the anisotropy field and the saturation magnetization decrease, but the coercivity increases up to 4 at.% Al and further alloying of Al leads to a decrease of the coercivity. Different substances like Al (metallic Al or Al2O3) modify the microstructure to different increase in the coercivity and especially to changes in the remanence. Alloying Al via metallic Al decreases the remanence, whereas via Al2O3) up to 4 at.%0 Al increases it. The Al additions inhibit atmospheric corrosion of the magnet. We have found that Al2O3 in sintered NdFeB magnet substantially improves the coercivity and the corrosion resistance with the improved remanence.