High–resolution study of [011] low–angle tilt boundaries in aluminium

The structure of [011] low–angle tilt boundaries in aluminium has been studied in bicrystals with different grain boundary planes (GBP). High–resolution electron microscopy using lattice–plane imaging and tilted illumination at 100 kV gave the fine structure of this type of boundary. Edge and 60° dislocations were always found : the (011) GBP is stable and has the lowest energy. The edge sessile dislocations showed no tendency to rotate in a thin foil and the elastic relaxation field was very well reproduced in the high resolution image. By contrast, a 60° dislocation tended to rotate away from the [011] direction in a thin foil as shown by the weak–beam teohnique: this rotation is limited by interaction with other dislocation segments. Splitting of the 60° dislocation, if it exists at all, is less than 8 å.