Direct Determination of the Reciprocal Lattice Spacing and the Radial Interference Distribution by the Fourier Method
AbstractA procedure for extracting the interference distribution from the X-ray diffraction line using measured instrumental and wavelength distributions has been applied to the study of residual stress in copper following extension.In the direct unfolding method the principal instrumental distributions due to the source and to specimen absorption are unfolded by the Fourier method. The remaining instrumental aberrations are extracted using the centroid displacements. The resultant scattering distribution is transformed by the relations of Mitchell and de Wolff and the spectral distribution unfolded. Conditions limiting the Fourier coefficients are applied to preserve stability. Measurements have been carried out with a diffractometer equipped with a diffracted beam monochromator.The 420 and 331 interference distributions in copper following 10% extension have been compared with those of stress - free material. The distributions are symmetric both in the annealed specimen and after extension. In extension the distributions are displaced by an amount equivalent to a surface compressive stress of 6 kg/mm2, The symmetry of the interference distributions indicates that the displacement is due to a macrostress distribution.
