To explore the feasibility of deep grain-size refinement in overcoming the problem of traditional Br-Hci trade-off in bulk permanent magnets,the effect of deformation temperature on the texture strength,grain refining,and magnetic properties of slow-deformed Nd-Fe-B magnets was systematically studied.As a result,strong textures with gradual grain refining from conventionally large size of DL=650 nm to small nanoscale size of DL=53 nm(DL denotes the lateral size of the aligned plate-like grains)are observed as the temperature reduces from Td=650℃to Td=450℃.Moreover,magnetic observations show a simultaneous increase in remanence and coercivity as the grain refines from DL=650 nm to DL=127 nm.The increase in coercivity results from the grain size refinement as well as the smaller aspect ratio of the plate-like grains,and the increase in remanence results from the improved texture homogeneity.As compared with the DL=650 nm magnets,the simultaneous increase in remanence and coercivity leads to optimum enhancements of 57％in coercivity,10％in remanence,and 25％in energy product,which demonstrate the feasibility of near-nanoscale grain refinement in overcoming the traditional BrHci trade-off for improved(BH)max values.The failure of higher coercivities in the DL≤80 nm magnets is closely related with the defect effects of the grain boundaries.Mechanisms explaining the grain refining and texture changing behavior were also discussed.

Fengqing Wang;Kanghua Chen;Juan Du;Jian Zhang

CAS Key Laboratory of Magnetic Materials and Devices,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences(CAS),Ningbo 315201,China;Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo 315201,China;State Key Laboratory for Powder Metallurgy,Central South University,Changsha 410083,China;Institute of Materials,Shanghai University,Shanghai 200444,China

稀土学报（英文版）

[1]Fengqing Wang;Kanghua Chen;Juan Du;Jian Zhang-.Simultaneous increase in remanence and coercivity during grain refining of Nd-Fe-B deformed magnets)[J].稀土学报（英文版）,2022(11):1763-1771

Hci,BrHci,coercivities

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