The dislocation processes in δ'-strengthened Al-rich alloys were studied by means of transmission electron microscopy. Thin foils were tensile-tested within the transmission electron microscope, and the configurations of dislocations and their glide behaviour were observed under full load. The average radii of the precipitates, and their volume fraction, were varied independently from 5 to 16nm and from 0.05 to 0.17, respectively. Two types of dislocation configuration were found: pairs of dislocations and single unpaired dislocations. All of the dislocations had Burgers vectors of ½<110>-type. The abundances of the configurations varied as a function of the precipitate volume fraction. Single dislocations predominated when the volume fraction was low, whereas high volume fractions favoured pairing. Cross-slip and double cross-slip were very frequent. When the volume fraction was low, it led to uncoupling of the 2 dislocations to form a pair.

in situ Transmission Electron Microscopy Observations of Dislocation Processes in δ'-Strengthened Aluminium-Lithium Alloys. H.Rösner, W.Liu, E.Nembach: Philosophical Magazine A, 1999, 79[12], 2935-51