The twinning in the intermetallic compound Al18Cr2Mg3 was observed and identified by transmission electron microscopy.The geometric description of the twinning in Al18Cr2Mg3 with 184 atoms per unit cell was investigat...The twinning in the intermetallic compound Al18Cr2Mg3 was observed and identified by transmission electron microscopy.The geometric description of the twinning in Al18Cr2Mg3 with 184 atoms per unit cell was investigated at atomic level.The classical theory of deformation twinning states that the net atomic displacements are divided into shear and shuffles during twinning.Based on the theory and the hypothesis of full mirror reflection symmetry,the displacement and angle of shuffle were calculated for each atom.The geometric calculation results show that all of the atoms in single crystal Al18Cr2Mg3 have to shuffle.Moreover,the calculation results can be divided into 22 groups,which do not show obvious regularity.展开更多
Electron irradiation effects on phase stability of the E （Al18Cr2Mg3） phase have been investigated by high- angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electro...Electron irradiation effects on phase stability of the E （Al18Cr2Mg3） phase have been investigated by high- angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electron microscopy （HRTEM）. The in situ HRTEM observations show that the Ala8Cr2Mg3 particles with different thickness undergo amorphization and dissolution under 300 keV electron irradiation at 25 ℃. The results indicate that the intermetallic compound Al18Cr2Mg3 is unstable under electron irradiation, and structural changes mainly depend on the thickness of particles. Amorphization in the thick particles is caused by a combination of chemical disordering and an increase in point defect concentration. Dissolution after amorphization in the thin particles is attributed to the diffusion of point defect towards the Al matrix.展开更多
基金financially supported by the 111 Project (No.B08040) of ChinaNational Natural Science Foundation of China (No.51071125)
文摘The twinning in the intermetallic compound Al18Cr2Mg3 was observed and identified by transmission electron microscopy.The geometric description of the twinning in Al18Cr2Mg3 with 184 atoms per unit cell was investigated at atomic level.The classical theory of deformation twinning states that the net atomic displacements are divided into shear and shuffles during twinning.Based on the theory and the hypothesis of full mirror reflection symmetry,the displacement and angle of shuffle were calculated for each atom.The geometric calculation results show that all of the atoms in single crystal Al18Cr2Mg3 have to shuffle.Moreover,the calculation results can be divided into 22 groups,which do not show obvious regularity.
基金financially supported by the 111 Project (No. B08040) of ChinaNational Natural Science Foundation of China (No. 51071125)
文摘Electron irradiation effects on phase stability of the E （Al18Cr2Mg3） phase have been investigated by high- angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electron microscopy （HRTEM）. The in situ HRTEM observations show that the Ala8Cr2Mg3 particles with different thickness undergo amorphization and dissolution under 300 keV electron irradiation at 25 ℃. The results indicate that the intermetallic compound Al18Cr2Mg3 is unstable under electron irradiation, and structural changes mainly depend on the thickness of particles. Amorphization in the thick particles is caused by a combination of chemical disordering and an increase in point defect concentration. Dissolution after amorphization in the thin particles is attributed to the diffusion of point defect towards the Al matrix.
