A CRYSTALLOGRAPHIC STUDY OF DISLOCATION CELL ARRANGEMENT IN ALUMINUM DEFORMED AT AN ELEVATED-TEMPERATURE

The arrangement of dislocation cells in a commercial aluminium alloy 1 145 subjected to uniaxial tensile deformation at 150 degrees C to a tr ue strain of 0.1 has been investigated using transmission electron mic roscopy and convergent beam electron diffraction. Both misorientations between neighbouring dislocation cells and misorientation gradients a cross the grain as well as dislocation boundary orientations have been analysed. As an example, illustrating general qualitative features of the deformation microstructure as a whole, results of a detailed crys tallographic analysis of a typical cell arrangement are presented. The results obtained in the study are compared to those available for sim ilar deformation conditions at room temperature and the validity of so me assumptions from the theory of low-energy dislocation structures is discussed. It is concluded that the observed cell structure has a com plex hierarchical character and neither misorientation vector distribu tions nor dislocation boundary orientations correspond to the simple c heckerboard arrangement of cells predicted by the above theory.