Information on deformation mechanisms in nanocrystalline Pd-10 % Au inferred from texture analysis

Abstract

There is still a lack of understanding of deformation mechanisms in nanocrystalline (nc) materials. Studies on microstructures formed in nc Pd–10% Au (grain size about 15 nm) after high pressure torsion revealed signatures of various deformation processes as cooperative grain boundary sliding (GBS), shear banding, dislocation slip and twinning. In order to estimate contributions of these processes to total strain, a comparison was made between torsion textures formed in nc and coarse grained cg) samples after identical shear strain. The textures were measured with synchrotron radiation. Intensities of characteristic components of the shear texture are two times stronger in the cg sample than in the nc one, indicating that dislocation slip is less significant in the nc sample. It is proposed that numerous planes of cooperative GBS revealed by TEM contribute to plasticity of nc alloy.