Effect of Al2O3 doping on resistivity and magnetic properties of sintered NdFeB magnets
Al2 O3-doped sintered NdFeB magnets were prepared by intergranular doping of Al2O3 into NdFeB alloy powder.Effect of Al2O3 doping on the resistivity,magnetic properties and microstructure of the NdFeB magnets was studied.The results show that the magnetic resistivity gradually increases with the increase of Al2O3 doping content,from 125.2 μΩ·cm without dopiong to 144.4 μΩ·cm when the Al2O3 doping content is 0.5 mass％,increasing by 15.3％.The coercivity of the magnets increases first and then decreases with the increase of Al2O3 doping content.The coercivity of the undoped magnet is 13.28 kOe,and when the Al2O3 doping content is 0.3 mass％,the coercivity reaches its maximum value of 14.97 kOe.Continuing to increase the Al2O3 doping content,the coercivity of the magnets begins to decreases.The magnet remanence gradually decreases with the increase of Al2O3 doping content,from 13.97 kGs without doping to 12.69 kGs when the Al2O3 doping content is 0.5 mass％.An appropriate content of Al2O3 doping is beneficial for inhibiting the grain growth of the magnets during the sintering,thereby refining the grain size,improving the coercivity of the magnets,and improving temperature stability to a certain extent.
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