It is still an open debate whether the 1:5 H cell boundaries(CBs)or the intersections of 1:3 R platelets and1:5 H CBs are the strong pining sites for the cellular nanostructured 2:17-type Sm-Co-Fe-Cu-Zr high temperatu...It is still an open debate whether the 1:5 H cell boundaries(CBs)or the intersections of 1:3 R platelets and1:5 H CBs are the strong pining sites for the cellular nanostructured 2:17-type Sm-Co-Fe-Cu-Zr high temperature permanent magnets despite that they have been widely applied in advanced industries since 1970 s.Herein,through tuning the volume fraction of Zr-enriched 1:3 R platelets by varying the second-step aging time,the pinning behavior in a model magnet Sm_(2.5)Co_(44.9)Fe_(21.5)Cu_(5.6)Zr_(3.0)(wt%)was investigated.The results show that the volume fraction of 1:3 R platelets can be effectively enlarged without changing the cell size(i.e.the volume fraction of CBs)by extending the aging time at 400℃.Micro scopic TEM characterizations co mbined with macro scopic magnetic measurements reveals that the locally thickened 1:3 R platelets after long-term second-step aging reduce the effective pinning area by interrupting the magnetic domain walls at CBs,weakening the average pinning strength and the coercivity of the magnet.Consequently,our work supports that the 1:5 H CBs act as the dominating pinning sites instead of the intersections of 1:3 R platelets and 1:5 H CBs,which may provide an important insight towards understanding the hard magnetism of pinning-controlled permanent magnets.展开更多
基金Project supported by the National Natural Science Foundation of China(52071256,51901170)the Opening Project of Key Laboratory of Magnetic Molecules and Magnetic Information Materials of the Ministry of Education,China(MMMM-202003)。
文摘It is still an open debate whether the 1:5 H cell boundaries(CBs)or the intersections of 1:3 R platelets and1:5 H CBs are the strong pining sites for the cellular nanostructured 2:17-type Sm-Co-Fe-Cu-Zr high temperature permanent magnets despite that they have been widely applied in advanced industries since 1970 s.Herein,through tuning the volume fraction of Zr-enriched 1:3 R platelets by varying the second-step aging time,the pinning behavior in a model magnet Sm_(2.5)Co_(44.9)Fe_(21.5)Cu_(5.6)Zr_(3.0)(wt%)was investigated.The results show that the volume fraction of 1:3 R platelets can be effectively enlarged without changing the cell size(i.e.the volume fraction of CBs)by extending the aging time at 400℃.Micro scopic TEM characterizations co mbined with macro scopic magnetic measurements reveals that the locally thickened 1:3 R platelets after long-term second-step aging reduce the effective pinning area by interrupting the magnetic domain walls at CBs,weakening the average pinning strength and the coercivity of the magnet.Consequently,our work supports that the 1:5 H CBs act as the dominating pinning sites instead of the intersections of 1:3 R platelets and 1:5 H CBs,which may provide an important insight towards understanding the hard magnetism of pinning-controlled permanent magnets.
