Investigation of texture in ECAP materials using neutron diffraction

The use of severe plastic deformation techniques such as equal channel angular pressing, has been shown to refine metal microstructures giving advantageous mechanical properties. Metals and alloys subjected to ECAP procedures can have very high yield strengths while maintaining substantial ductility, a unique and attractive combination. However, the implicitly large deformations (the application of repeated shear strains of similar to1 are typical) make prediction of the resulting mechanical properties difficult. In particular, modeling the polycrystalline texture evolution and microstructural strain response is challenging. In this paper, results are presented from a neutron diffraction study on aluminum, copper, nickel and beryllium processed by ECAP. Specific attention is given to the evolution of the bulk texture after one pass and the effect of the initial texture. The neutrons probed volumes on the order of cubic centimeters and therefore provided texture and strain information averaged over the bulk of the sample. The results are discussed in the context of a visco-plastic self-consistent model.