A systematic procedure was developed to evaluate the density of planar defects together with dislocations and crystallite or sub-grain size by X-ray line profile analysis in face-centered cubic crystals. Powder diffraction patterns were numerically calculated by using the DIFFAX software for intrinsic and extrinsic stacking faults, and twin boundaries for the first 15 Bragg reflections up to 20% fault density. It was found that the Bragg reflections consisted of five sub-reflection types categorized by specific selection rules for the hkl indices in accordance with the theory of Warren. It was shown that the profiles of the sub-reflections were Lorentzian-type functions. About 15000 sub-reflections were evaluated for their full widths of half-maxima and their positions relative to the exact Bragg angle. These values were parameterized as a function of the density and type of planar faults. A whole profile fitting procedure, previously worked out for determining the dislocation structure and crystallite size distributions, was extended for planar fault by including these data into the software. The method was applied to evaluate twin densities in nanocrystalline and sub-micron grain-size Cu specimens. It was found that twinning became substantial under a critical crystallite or sub-grain size of about 40nm, in accordance with other observations.

Stacking Faults and Twin Boundaries in FCC Crystals Determined by X-Ray Diffraction Profile Analysis. L.Balogh, G.Ribárik, T.Ungár: Journal of Applied Physics, 2006, 100[2], 023512 (10pp)