In-situ high-energy X-ray diffraction study of the early-stage decomposition in 2:17-type Sm-Co-based permanent magnets

Local Phase Segregation Induced by Ion Milling in 2:17-Type Sm-Co Based Magnets

“…In addition, the nano-sized structural defects generated during the phase decomposition process also play an important role in the magnetic properties of the 2:17-type Sm-Co based magnets, especially the remanent stacking faults at the cell edge [10][11][12]. Since these crystalline phases and defects are very small in size (e.g., the thickness of the 1:5H phase is usually smaller than 10 nm) and the structures of the coherent 1:5H and 2:17R phases are similar and their lattice parameters are approximately equal [13,14], it is difficult to perform the specific microstructure by scanning electron microscopy or conventional X-ray diffraction technologies. Thus, transmission electron microscopy (TEM) and highresolution transmission electron microscopy (HR-TEM) are indispensable to reveal the true structure of the 2:17-type Sm-Co based magnets [3][4][5][7][8][9][10][11][12][13]15].…”

“…In addition, the nano-sized structural defects generated during the phase decomposition process also play an important role in the magnetic properties of the 2:17-type Sm-Co based magnets, especially the remanent stacking faults at the cell edge [ 10 , 11 , 12 ]. Since these crystalline phases and defects are very small in size (e.g., the thickness of the 1:5H phase is usually smaller than 10 nm) and the structures of the coherent 1:5H and 2:17R phases are similar and their lattice parameters are approximately equal [ 13 , 14 ], it is difficult to perform the specific microstructure by scanning electron microscopy or conventional X-ray diffraction technologies. Thus, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) are indispensable to reveal the true structure of the 2:17-type Sm-Co based magnets [ 3 , 4 , 5 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 15 ].…”

“…However, the TEM (or HR-TEM) is not risk-free, in terms of introducing microstructural artifacts, especially during the TEM specimen preparation process. Generally, the thin film specimens for TEM examinations of the 2:17-type Sm-Co based magnets are fabricated by ion milling or focused ion beam, since these magnets are too brittle to suffer electropolishing [ 4 , 5 , 7 , 8 , 10 , 11 , 12 , 13 ]. Although the energy used for ion milling or focused ion beam is relatively low (2–6 keV), the possible structure damage can be easily introduced into metallic materials since the temperature rising of the specimen surface is unavoidable during the ion milling process.…”