The role of deformation twinning in the texture evolution of pure polycrystalline Ag subjected to equal channel angular extrusion (route A, three passes) was examined. Microstructural characterization using electron back-scattering diffraction and transmission electron microscopy revealed a high twinning activity in every pass, as well as significant grain refinement. Polycrystal modelling, combined with experimental analysis, showed that texture evolution was the result of slip and deformation twinning that occurred in every pass. It was shown that the primary consequence of twinning was the reorientation of the A1 ideal component into the A2 orientation. This process resulted in a weak A1 and a strong A2 component. This twinning mechanism was repeated in each pass, aided by the strain path changes associated with route A; and an apparent regeneration of the microstructure. As a result, with each pass the A1 and C ideal shear components weakened, whereas the B/¯B components strengthened. These tendencies were distinct from those of high stacking-fault energy face-centered cubic metals such as Al, Cu and Ni.

Role of Twinning on Texture Evolution of Silver during Equal Channel Angular Extrusion. I.J.Beyerlein, L.S.Tóth, C.N.Tomé, S.Suwas: Philosophical Magazine, 2007, 87[6], 885-906