Influence Of Low-melting-point Pr₇₀Cu₃₀ Alloys On Microstructure And Magnetic Property Of Hot-deformed Nd₂Fe₁₄B/?-Fe Magnets

Nanocomposite exchange coupled magnets consisting of a fine mixture with nano-scale hard-and soft-magnetic phases have attracted much attention due to their potentially high energy products.However,the difficulty to obtain the texture for Nd₂Fe₁₄B phase and a low coercivity limit the realization of high-energy product in nanocomposite magnets.Hence,obtained the texture for Nd₂Fe₁₄B phase while maintaining high coercivity is of significance for preparing high-performance anisotropic nanocomposite magnets.In this paper,we try to diffuse low melting point eutectic Pr₇₀Cu₃₀ alloys into the grain boundary of anisotropic Nd₂Fe₁₄B/?-Fe nanocomposite magnets prepared by a combination of hot pressing,hot deformation and thermal annealing.The influence of low-melting-point Pr₇₀Cu₃₀ alloys on microstructure and magnetic properties of hot-deformed Nd₂Fe₁₄B/?-Fe magnets have been studied by employing X-ray diffraction?XRD?,transmission electron microscopy?TEM?and vibrating sample magnetometer?VSM?techniques.Using MQP15-7 nanocrystal ribbons(a mass fraction of 4 wt%,5 wt%and 6 wt%Pr₇₀Cu₃₀ alloys were mixed with together)as the precursors,anisotropic Nd₂Fe₁₄B/?-Fe nanocomposite magnets were prepared by hot pressing and hot deformation.The additive of Pr₇₀Cu₃₀ alloys?a mass fraction of 5 wt%?not only makes hot-deformed magnets achieve a high coercivity increasing from 6.5 kOe to 8.2 kOe,but also promotes the formation of crystallographic texture in the process of hot deformation and enhances magnetic anisotropy,the relative intensity ratio of I_?004?/I_?220?increasing from 80%to 195%,and thus achieves the maximum energy product 19.9 MGOe.Using Nd₉Fe₈₂Co₃B₆ amorphous ribbons(a mass fraction of 4 wt%,6 wt%and 8wt%Pr₇₀Cu₃₀ alloys were mixed with together)as the precursors,anisotropic Nd₂Fe₁₄B/?-Fe nanocomposite magnets were prepared by a combination of hot pressing,hot deformation and thermal annealing.The crystallographic texture for Nd₂Fe₁₄B phase of hot-deformed magnets containing Pr₇₀Cu₃₀ alloys,has been enhanced after thermal annealing for 12 h.The relative intensity ratio of I_?004?/I_?220?increasing from 113%to 142%,after the hot-deformed magnets(a mass fraction of 6 wt%Pr₇₀Cu₃₀ alloys)annealed for 12h,and thus the remanence of magnets was increased from 9.7 kG to11.5 kG,and the maximum magnetic energy product was increased from 14.1 MGOe to 21.3 MGOe,increasing by 38%as compared to the magnets,after thermal annealing for 12 h,without Pr₇₀Cu₃₀ alloys.