摘要
The microstructure of twinning as well as the phase boundary between 1:5 H and 2:17 R phase in Fe-rich Sm_(2)Co_(17)-type magnets was characterized at atomic scale using nanobeam diffraction and highresolution STEM-HAADF imaging,and the reason for the dramatic increase of coercivity during slow cooling was investigated based on the microchemistry analysis.The twinning relationship in the 2:17 R phase originates from ordered substitution of Sm atoms by Co-Co atomic pairs on every three(3033)and(3033)planes,leading to formation of two corresponding equivalent twin variants.The basal plane of the 2:17 R phase,the 1:3 R platelet phase across the 2:17 R cell and the 1:5 H cell boundary phase between two adjacent 2:17 R cells all can act as effective twin boundary.The cell boundary phase is precipitated along the pyramidal habit plane,and a fully coherent phase boundary(PB)is formed between the 1:5 H and 2:17 R phases with the orientation relationship to be PB//(1121)1:5 H//(1011)_(2):17 R.The phase boundary may either be parallel to or intersect with the pyramidal planes occupied by Co-Co atomic pairs.The substantial increase of coercivity during slow cooling is ascribed to the development of large gradient of the elements concentration within the cell boundary phase,resulting in large gradient of domain wall energy,and thus the pinning strength of the cell boundary phase against magnetic domain wall motion is significantly enhanced.
基金
Project supported by Zhejiang Province Public Welfare Technology Application Research Project(LGC20E010002)
National Natural Science Foundation of China(51877094)。
作者简介
Corresponding author:Zhuang Liu.E-mail addresses:zliu@nimte.ac.cn;Corresponding author:Huanming Lu.E-mail addresses:hmlu@nimte.ac.cn;Corresponding author:Aru Yan.E-mail addresses:aruyan@nimte.ac.cn。
