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The partially recombined compacts with ultrafine grain size were taken advantage of preparing anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure.Because of the ultrafine grain size of the precursors,the partially recombined phases could quickly achieve recombination.The results suggested that the newly recombined Nd_2Fe_(14)B grains with fine grain size could undergo deformation immediately during the desorption-recombination reaction,and then an obvious anisotropy and uniform alignment would be obtained.The magnetic properties,(BH)_(max)=214 kJ/m~3,B_r= 1.26 T,H_(cj)=463 kA/m,were obtained after being treated for 5 min at 820 ℃ in high vacuum under low pressure less than 26 MPa.Microstructures of the magnets were analyzed using X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM) respectively.Magnetic measurements were carried out using a vibrating sample magnetometer(VSM) with the maximum field of 2.88 T.Accurate phase contents were measured by a Mossbauer spectrometer.
The partially recombined compacts with ultrafine grain size were taken advantage of preparing an anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure.Because of the ultrafine grain size of the precursors, the partially recombined may could quickly achieve recombination. The results suggested that the newly recombined Nd_2Fe_ (14) B grains with fine grain size could be deformed immediately during the desorption-recombination reaction, and then an obvious anisotropy and uniform alignment would be obtained. The magnetic properties, (BH) _ (max ) = 214 kJ / m ~ 3, B_r = 1.26 T, H_ (cj) = 463 kA / m, were obtained after being treated for 5 min at 820 ° C in high vacuum under low pressure less than 26 MPa. Microstructures of the magnets were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Magnetic measurements were carried out using a vibrating sa mple magnetometer (VSM) with the maximum field of 2.88 T. Accurate phase contents were measured by a Mossbauer spectrometer.