Kikuchi Maps for hcp and bcc Crystals

Kikuchi maps have been obtained for bcc and hcp crystals, and their applications to the determination of orientations and Burgers vectors are described. The hcp map is particularly useful and time-saving, and enables orientations to be rapidly and uniquely determined. These cannot be readily obtained from hcp spot patterns in many cases. It is shown that the basal-plane orientation, which can be tilted by about 20 deg to any of the six 〈11̄03〉 poles, is sufficient to provide the unique solution for determining any of the possible 21 Burgers vectors in hcp structures, and that the forbidden 〈1̄21̄1〉 reflections formed by double diffraction can be utilized to simplify such determinations. Kikuchi maps become increasingly valuable for investigating materials of crystal structures which have lower symmetry than that of the cubic systems.