Research Of The Dislocation Structures Of Deformed FCC Metals

The formation and evolution of dislocation boundaries are a fundamentalproblem in research into plastic deformation of metals. It is known that themorphologies and characters of dislocation boundaries in FCC metals ofmedium-to-high stacking fault energy deformed to low and intermediatestrains are strongly dependent on the grain orientation, and this orientationdependence is further revealed as being slip system dependent, i.e. differentslip systems are activated in grains with different orientations.In the current work, dislocation structures and their relationship withgrain orientation in rolled polycrystalline aluminium and deformedcolumnar-grained nickel are investigated with TEM and SEM, and theobservation are compared with previous studies of aluminium and copper tofurther understand the orientation dependence of deformed FCC metals. Thedifferences in the dislocation structures of aluminium, nickel, and copper, andthe cause of the differences are also analyzed.Detailed TEM characterization of dislocation boundaries have also beencarried out for grains with certain chosen orientations (Cube, Goss) in rolledaluminium. The Frank formula is used to calculate the dislocation linedirection and dislocation density for possible dislocation configuration withinthe boundaries by using the boundary parameters (misorientation and normal).The possible active slip systems are then estimated by Schmid factors. Thedislocation content (Burgers vectors and dislocation density) have beendetermined in TEM and compared with the calculated results to establish therelationship between grain orientation, boundary type and dislocation content.