Investigation of dislocation networks in dispersion-strengthened aluminum

Dislocation networks in dispersion-strengthened aluminum produced by hot extrusion were investigated by transmission electron microscopy. Owing to the close dislocation spacings, the weak-beam technique had to be employed. Burgers vectors and line directions were determined in the as-produced state and after annealing above the extrusion temperature. The dislocation networks show remarkable regularity and can be grouped into three different types according to their dislocation arrangement, spacings and Burgers vectors. One type of the dislocation networks containing 60° dislocations disappears during annealing and therefore is suggested to be responsible for the different mechanical properties of the material before and after heat treatment.