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Effect of die-upset level on the mechanical properties and microstructure of Nd-Fe-B magnets prepared by spark plasma sintering 总被引:1,自引:0,他引:1
The mechanical properties and microstructure of Nd-Fe-B magnets produced at various die-upset levels have been investigated. The results showed that the Vickers hardness and the fracture toughness of Nd-Fe-B magnets first increased, and then rapidly decreased with the increase in die-upset level. The optimum Vickers hardness and the fracture toughness were obtained at the die-upset level of 40%. The peak intensity of the (1 0 5) peak is the maximum value, the relative intensities of the (2 1 2), (2 1 4) and (3 1 4) peaks decline and the relative intensity of the (0 0 6) peak increases with the increase in die-upset level. The microstructures show that the variation in the size of small spherical grains is not obvious, and the volume fraction of small spherical grains declines gradually with the increase in die-upset level. 相似文献
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Yilong Ma Jun Li Chaoying Li Linhua Chu 《Journal of magnetism and magnetic materials》2010,322(16):2419-2422
The magnetic properties and microstructure were studied for bulk Nd11.5Fe72.4Co9Nb1B6.1 magnets synthesized by hot-pressing and subsequent die-upsetting the melt-spun ribbons with additions of three kinds of low-melting-point metal (Zn, Al and Sn). Die-upset Nd11.5Fe72.4Co9Nb1B6.1 magnets have low magnetic properties since they have an inhomogeneous microstructure with many coarse grains. The microstructure of die-upset magnets remains almost unchanged with Al and Sn additions, which only have negative effects on the magnetic properties. Different from Al and Sn additions, Zn addition changes the phase composition of the starting melt-spun powers due to the reaction of Zn and Nd2Fe14B during hot-pressing and hot-deforming and enhances the development of the desired [0 0 1] texture and improves the microstructure of die-upset magnets. As a result, an anisotropic magnet with good maximum energy product (221 kJ/m3) and high coercivity (670 kA/m) is obtained by adding 2 wt% Zn to the Nd11.5Fe72.4Co9Nb1B6.1 alloy. 相似文献
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