Computer simulation of coercivity improvement due to microstructural refinement

The effect of the presence of a non-magnetic phase at multi-junctions of Nd2Fe14B grains on the demagnetization process of Nd-Fe-B magnets was investigated by micromagnetic simulations, while varying the size of the non-magnetic phase and the Nd2Fe14B grains. While the demagnetizing field created by the non-magnetic phase assisted the nucleation of a reverse domain, its effect was only significant when its size exceeded a critical value. This critical size effect can be explained by a change in the spatial distribution of the demagnetizing field. In addition, the calculations indicated that microstructural refinement would also increase the coercivity. This increase in coercivity could also be attributed to a change in the spatial distribution of the demagnetizing field due to the presence of a non-magnetic phase. Changes in the spatial distribution of the demagnetizing field due to such a non-magnetic phase could represent a mechanism by which microstructural refinement leads to increased coercivity.

[1]  H. Sepehri-Amin,et al.  Micromagnetic simulations on the grain size dependence of coercivity in anisotropic Nd–Fe–B sintered magnets , 2014 .

[2]  T. G. Woodcock,et al.  Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets , 2014, 1603.08248.

[3]  Thomas Schrefl,et al.  Effect of Nd content on the microstructure and coercivity of hot-deformed Nd–Fe–B permanent magnets , 2013 .

[4]  H. Sepehri-Amin,et al.  Grain boundary and interface chemistry of an Nd–Fe–B-based sintered magnet , 2012 .

[5]  正基 中野,et al.  Nd-Fe-B磁石の磁化反転過程に及ぼす静磁気相互作用の影響 —計算機シミュレーション— , 2012 .

[6]  康裕 宇根,et al.  結晶粒微細化によるNd-Fe-B焼結磁石の高保磁力化 , 2012 .

[7]  A. Sakuma,et al.  First principles study on the local magnetic anisotropy near surfaces of Dy2Fe14B and Nd2Fe14B magnets , 2011 .

[8]  T. G. Woodcock,et al.  The role of local anisotropy profiles at grain boundaries on the coercivity of Nd2Fe14B magnets , 2010 .

[9]  諭 杉本.  Nd-Fe-B系焼結磁石における省Dy技術の研究動向 , 2010 .

[10]  A. Yan,et al.  Enhanced magnetic properties and bending strength of hot deformed Nd-Fe-B magnets with Cu additions , 2010 .

[11]  Thomas Schrefl,et al.  Micromagnetics simulation of high energy density permanent magnets , 2000 .

[12]  H. Fukunaga,et al.  Effect of strength of intergrain exchange interaction on magnetic properties of nanocomposite magnets , 1999, IEEE International Magnetics Conference.

[13]  K. Ramstöck,et al.  Corners and nucleation in Micromagnetics , 1998 .

[14]  T. Schrefl,et al.  Overview of Nd-Fe-B magnets and coercivity (invited) , 1996 .

[15]  S. Kikuchi,et al.  Some Considerations on the Directional Control of a Linear Parametric Motor , 1994, IEEE Translation Journal on Magnetics in Japan.

[16]  T. Schrefl,et al.  Nucleation of reversed domains at grain boundaries , 1993 .

[17]  T. Schrefl,et al.  Nucleation fields and grain boundaries in hard magnetic materials , 1993 .

[18]  H. Kronmüller,et al.  Size dependence of the nucleation field of rectangular ferromagnetic parallelepipeds , 1991 .

[19]  H. Fukunaga,et al.  Effect of Magnetic Inhomogeneity on Magnetization Reversal in Sintered Nd-Fe-B Magnet –Numerical Approach– , 1990 .

[20]  M. Sagawa,et al.  Analysis of the magnetic hardening mechanism in RE-FeB permanent magnets , 1988 .