DISLOCATION DENSITY AND LONG-RANGE INTERNAL-STRESSES IN HEAVILY COLD-WORKED CU MEASURED BY X-RAY-LINE BROADENING

A well proven method of high resolution X-ray line profile analysis is applied to large-strain straight rolled samples of polycrystalline co pper. Both the obtained dislocation densities and long-range internal stresses show a monotonous increase within the strain stage IV, and th en a levelling off in stage V. The local stresses of cell walls and ce ll interiors are found to increase within stage IV even in relation to the macroscopic stress. Together with the measured values of volume f raction of cell walls, the strengthening in stage IV turns out to aris e mainly from the cell interior, although it is clearly related to the increase of total dislocation density and not so much to dislocation rearrangements which enhance the stress field.