Effect of two-step annealing on magnetic properties of Pr-Fe-B base hot-rolled magnet

Yuri, T.; Ohki, T.

doi:10.1109/20.280923

Cited by 9 publications

(1 citation statement)

References 3 publications

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“…It is known that if Nd is substituted by Pr in RE-Fe-Cu-B alloys (RE: rare-earth), high coercivity can be achieved in bulk state by specific annealing treatments. [25][26][27][28][29][30][31][32][33] Nd-Fe-B and Pr-Fe-B ternary phase diagrams are quite similar; [34,35] same holds for the magnetic properties of the Pr 2 Fe 14 B and Nd 2 Fe 14 B phases. The addition of Cu to the ternary system strongly improves the hard magnetic properties (coercivity) due to formation of additional grain boundary phases (e.g., RE-Cu low melting eutectics [36] or (Nd,Pr) 6 Fe(Cu, Al, Ga) 14 in commercial magnets [37] ), which separate the hard magnetic grains.…”

Section: Introductionmentioning

confidence: 99%

Design and Qualification of Pr–Fe–Cu–B Alloys for the Additive Manufacturing of Permanent Magnets

Schäfer

Skokov

Liu

et al. 2021

Adv Funct Materials

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The direct use of an advanced binder‐free additive manufacturing technique, namely laser powder bed fusion (L‐PBF), does not easily allow obtaining variously shaped, fully dense Nd–Fe–B magnets with high coercivity. The process inherently leads to the re‐melting of the powder and appearance/disappearance of undesired/desired microstructural features responsible for low and large coercivity. In this work, the development of a useful microstructure responsible for high coercivity in Pr21Fe73.5Cu2B3.5 and Nd21Fe73.5Cu2B3.5 alloys and a possible way to produce fully dense permanent magnets via additive manufacturing processes is demonstrated using: (i) suction casting technique, which provides a high cooling rate and thus similar microstructures as in L‐PBF but requires only very small amounts of powder; (ii) conventional L‐PBF processing using kg of powder, and (iii) a subsequent annealing treatment that is similar to a conventional sintering treatment. The subsequent heat treatment is necessary to develop high coercivity by forming a novel microstructure: hard magnetic (Nd,Pr)2Fe14B grains embedded in a matrix of intermetallic (Nd,Pr)6Fe13Cu phase. Furthermore, it is demonstrated that Pr21Fe73.5Cu2B3.5 exhibits a higher coercivity than Nd21Fe73.5Cu2B3.5 because of a finer and more homogeneous grain size distribution of the Pr2Fe14B phase. The final L‐PBF printed Pr21Fe73.5Cu2B3.5 samples provide a coercivity of 0.75 T.

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