Extended Data Fig. 8: Ruling out other possible sources for the additional intensities.
From: On the origin of diffuse intensities in fcc electron diffraction patterns
(a,b) Cryostage TEM down the <111> zone of solution annealed Alloy 690 aged at 475 °C for 3,000 h. Examined at (a) −192 °C and (b) 23 °C, showing no obvious change in the \({}^{1}{ / }_{3}\){422} diffuse intensities. (c,d) An examination of Kikuchi band intersections and their contribution to \({}^{1}{ / }_{3}\){422} diffuse scattering in B = [111] SADPs. (c) A Kikuchi band simulation overlaid on an experimental SADP, showing the (d) decoupling of the Kikuchi band intensities and diffuse scattering. (e-i) Precession experiments on the pure aluminum sample to remove dynamical effects on the [111] SADP. The angles of (e) 0, 0.5 (f), 1.5 (g) and 3 (h) degrees were used. The intensity profile shown in (h) is shown in (i), with the arrows indicating the additional intensities that, although less evident, are still present. (j-l) TEM examination of the effect of foil thickness on \({}^{1}{ / }_{3}\){422} diffuse scattering in Alloy 690. (j) BFTEM from region of interest, showing the two locations where the thickness was measured, along with (k,l) the selected area diffraction patterns corresponding to these two locations. In (l) the SADP was specifically taken slightly off-axis, to ensure Kikuchi band intersections were not contributing to the \({}^{1}{ / }_{3}\){422} intensities. The chemical composition of the Alloy 690 used in this work is given on table (m).
