Microstructure and texture evolution in ECAE processed A5056

Equal channel angular extrusion (ECAE) represents an effective means of mic rostructural refinement through severe plastic deformation. In aluminum bas ed alloys microstructures obtained by this process generally result in inte resting and remarkable combinations of mechanical properties, such as for i nstance enhanced strength together with high levels of ductility. In the pr esent investigation, the evolution of the tensile properties, microstructur es and crystallographic textures during ECAE has been studied for an Al-Mg based workhardening type alloy (A5056) by metallographic observation, trans mission electron microscopy (TEM) and X-ray diffraction. The mechanical and microstructural characteristics of these alloys have been compared to extr udates of the same material prepared by conventional extrusion. The results show that dynamic recovery and the development of subgrains, mainly separa ted from each other by low angle grain boundaries, play an important role w ith respect to the formation of the ultrafine microstructures observed. No evidence for recrystallization and the nucleation of new grains occured up to pressing temperatures of 300 degrees C and very sharp deformation textur es were found to develop. Similar to rolling deformation a transition from a pure metal type texture to an alloy type texture in function of the defor mation degree occurs. The formation of these ECAE-textures is discussed on the basis of the Taylor theory of polycrystalline deformation. (C) 2000 Els evier Science S.A. All rights reserved.