Effects of PrNdFeCuGaB Addition at Grain Boundaries on the Magnetic Properties and Microstructure of NdFeB Magnets AITranslate

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Chinese Library Classification Number:TM273[一般工业技术]

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In order to improve the coercivity of sintered NdFeB magnets without adding heavy rare earth elements,this study adopted the grain boundary addition method to incorporate PrNdFeCuGaB alloy powders with different mass fractions(0,2%,4%,6%,and 8%)into NdFeB magnetic powders,and prepared sintered NdFeB magnets.The regulatory effects of PrNdFeCuGaB alloy addition content on the magnetic properties and microstructure of the magnets were systematically investigated.Combining the thermal activation theory,the intrinsic correlation between magnetic properties and microstructure was revealed.The results show that the matrix phase of the NdFeB magnets remains Nd₂Fe₁₄B regardless of the PrNdFeCu-GaB alloy addition content.The addition of PrNdFeCuGaB alloy optimizes the distribution of the RE-rich phases in the magnets,transforming them from an initially agglomerated morphology to a continuous striplike structure.These phases are distributed at the interfaces between adjacent matrix phase grains,resulting in more continuous and distinct grain boundaries.With the increase in PrNdFeCuGaB alloy addition content,the coercivity of the NdFeB magnets first increases and then decreases.The magnet achieves the optimal magnetic properties when the addition content of PrNdFeCuGaB alloy reaches 6%:B_r=13.85 kGs,H_cj=14.38 kOe,and(BH)_max=46.84 MGOe.The improvement in coercivity is attributed to two aspects:On the one hand,Pr atoms diffuse into the matrix phase to form a(Pr,Nd)₂Fe₁₄B shell layer,which enhances the interfacial anisotropy of the matrix phase grains.On the other hand,the formation of the(Pr,Nd)₆Fe₁₃Ga phase consumes the free Fe elements in the grain boundary regions,which allows the low-melting-point Ga and Cu elements to combine with Nd and Pr and migrate to the grain boundaries.This process forms a thin non-magnetic grain boundary layer between adjacent grains,which weakens the exchange coupling effect and strengthens the decoupling effect among the matrix phase grains.