Application of convergent-beam electron diffraction to the detection of lattice parameter changes in hexagonal close-packed metals

Abstract

Convergent beam electron diffraction (CBED) patterns have been used in several different applications to materials problems (summarised by Steeds) and has more recently been used to quantify shifts in the lattice parameters of cubic materials (e.g. 2). This technique has proved highly sensitive to such changes, capable, via the use of very simple geometrical computer simulations, of the detection and quantification of changes in lattice parameters of hexagonal alloys.Alloy systems based on zinc and titanium were used. A simple geometrical computer simulation was used to quantify the shifts, ignoring dispersion surface effects, in the higher order Laue zone (HOLZ) lines upon change in the lattice parameters. X-ray diffraction data from each of the alloys was obtained to provide a standard for comparison. The sensitivity of each zone axis pattern to changes in either a or c was determined from the magnitude of the HOLZ line shifts in the CBED pattern.