Precise determination of extended dislocation boundary plane in transmission electron microscopy

Abstract

The crystallographic plane of extended planar dislocation boundaries can be determined from the boundary trace and electron diffraction when the boundaries are exactly parallel to the beam direction (edge on). It is proposed to combine observations of sample tilt induced change in both projected boundary thickness and boundary spacing for identification of the edge on condition and the boundary crystallographic plane. The boundary crystallographic and macroscopic planes have been determined for two selected grains with similar grain orientations in tensile deformed aluminium. The determined boundary crystallographic planes are similar for the two grains, and in both cases the boundaries are more closely aligned with the active slip plane than with the macroscopically most stressed plane. These results suggest that the boundary crystallographic plane is more important than the macroscopic plane and that grain orientation has a strong effect on the occurrence of the preferred boundary crystallographic plane.