THE EFFECT OF STACKING-FAULT ENERGY ON THE MICROSTRUCTURAL DEVELOPMENT DURING ROOM-TEMPERATURE WIRE DRAWING IN CU, AL AND THEIR DILUTE ALLOYS

The effect of stacking fault energy (SFE) on the evolution of microstr uctures during wire drawing at room temperature has been studied in pu re aluminium, pure copper and Cu-2.2% Al and Cu-4.5% Al alloys which c overs a range of SFE values from 4 to 166 mJ m(-2). The compositions a re expressed in atomic parts per million by weight. The microstructure s have been characterized from samples obtained by deforming rods of t hese materials to true wire drawing strain values of up to 1.47. A dec rease in the SFE value changes the deformation mechanisms from the for mation of cell structure and their size refinement in a high SFE mater ial to the formation of deformation bands and deformation twins in a l ow SFE materials. The Cu-2.2% Al alloy deforms by deformation bands at low true strain values while deformation twins within the bands contr ol the deformation mechanisms at higher true strain values. The alloy, Cu-4.5% Al, with the lowest SFE value deforms only by deformation twi ns even at low true strain values and the presence of overlapping and intersecting deformation twins are the dominating features as the rods are drawn to higher true wire drawing strains.