Role of twinning on texture evolution of silver during equal channel angular extrusion

The role of deformation twinning in the texture evolution of pure polycrystalline silver subjected to equal channel angular extrusion (Route A, three passes) has been examined. Microstructural characterization using electron backscattering diffraction and transmission electron microscopy revealed high twinning activity in every pass, as well as significant grain refinement. Polycrystal modelling combined with experimental analysis shows that texture evolution is a result of slip and deformation twinning that occurs in every pass. It is shown that the primary consequence of twinning is the reorientation of the $A_1$ ideal component into the $A_2$ orientation. This process results in a weak $A_1$ and a strong $A_2$ component. This twinning mechanism is 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 $A_1$ and C ideal shear components weaken, whereas the B/B components strengthen, tendencies that are distinct from those of high stacking fault fcc metals like Al, Cu and Ni