Grain-resolved elastic strains in deformed copper measured by three-dimensional X-ray diffraction

This X-ray diffraction study reports the grain-resolved elastic strains in about 1000 randomly oriented grains embedded in a polycrystalline copper sample. Diffraction data were collected in situ in the undeformed state and at a plastic strain of 1.5% while the sample was under tensile load. For each grain the centre-of-mass position was determined with an accuracy of 10 μm, the volume with a relative error of 20%, the orientation to 0.05° and the axial strain to 10− 4. The elastic strain along the tensile direction exhibited a grain orientation dependence with grains within 20° of <100> carrying the largest strain. While the width of the strain distribution for all grains did not change upon plastic loading, the grain-resolved data show a significant widening of the distribution evaluated for small subsets of initially elastically similar grains. This widening appears independent of the grain orientation.

Research Highlights
► X-ray diffraction study of ~ 1000 Cu grains during in situ plastic deformation.
► Grain averaged positions, orientations, volumes and elastic strain tensors derived.
► Both lattice rotation and axial strain depend on the initial grain orientation.
► Grains within 20° of <100> carry the largest elastic strain along the tensile axis.
► The results enable evaluation and development of polycrystal plasticity models.