In Situ Measurements Of X-Ray Peak Profile Asymmetry From Individual Grains

Two copper samples, pre-deformed in tension to 5% plastic strain, are subjected to an in situ tensile deformation of 1% plastic strain while X-ray peak profiles from individual bulk grains are obtained. One sample is oriented with the in situ tensile axis parallel to the pre-deformation axis, and peak profiles are obtained with the scattering vector parallel to this direction. The profiles show the expected asymmetry explained by the composite model as caused by intra-grain stresses. The other sample is oriented with the in situ tensile axis perpendicular to the pre-deformation axis, and peak profiles are obtained with the scattering vector parallel to the in situ tensile axis. In this case the profiles initially show an opposite asymmetry, but during the in situ deformation the asymmetry reverses sign as the deformation under new loading conditions leads to changes in the intra-grain stresses.