Sputtering and Diffusion Treatment of Ultra-high Performance NdFeB Magnets
The surface of NdFeB magnet was coated with heavy rare earth Tb by magnetron sputtering,and then the ultra-high performance magnet with comprehensive performance of nearly 80[Hcj/kOe+(BH)max/MGOe]was obtained by diffusion heat treatment.The internal mechanism was analyzed.The influence of heat treatment process on the microstructure and magnetic properties of magnets was studied by scanning electron microscope backscattering electron imaging technology,and the mechanism of coercivity improvement and microstructure evolution law were discussed.The results show that,the coercivity of the magnet after diffusion treatment is sig-nificantly improved,the remanence is not significantly reduced,the temperature stability is significantly im-proved,the microstructure is obviously optimized,and a more continuous and uniform Nd-rich phase structure is formed,which effectively inhibits the magnetic coupling effect of the main phase grains.Tb enrichment at the surface region rather than the center of 2∶14∶1 grains not only increases the coercivity by enhancing the local magnetocrystalline anisotropy field,but also maintains the remanence.
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