In situ generation of intergranular strains in an Al7050 alloy

We have measured the evolution of intergranular strains, both parallel and transverse to the stress axis, in the f.c.c. alloy Al7050 under uniaxial tension by neutron diffraction. Intergranular strains of opposite signs are observed for [111] and [002] grains because of the anisotropy of plastic deformation existing in Al7050. The angular variation of the strain state of the tensile samples has also been measured and axial symmetry about the stress axis is observed. The experimental results indicate the magnitudes of the intergranular strains are large and easily measured, even though the materials are macroscopically stress free. The experimental results are compared with simulations based on the elasto-plastic self-consistent (EPSC) model of Turner and Tomé. The model is in qualitative agreements with the experiments, but tends to overestimate the magnitudes of the intergranular strain.