IMPROVED X-RAY AND ELECTRON-DIFFRACTION METHODS FOR TWIN DETERMINATION IN HEXAGONAL CRYSTALS

Two improved methods of characterizing twin orientations in deformed crystals have been developed and compared; the back-scattered Kikuchi electron diffraction method in a standard scanning electron microscope and a new high-resolution X-ray pole-figure technique. Comparative tests on titanium and magnesium crystals deformed in plane strain compression up to high strains demonstrate their complementary features. The backscattered Kikuchi diffraction technique, which combines imaging and microdiffraction, is well adapted to localized twin-orientation studies in both single and polycrystals after careful surface preparation. The high-resolution X-ray pole figures can be used for more quantitative studies of twinned volume fractions, including very fine twins, in crystallographically oriented samples such as deformed single crystals or large-grained polycrystals.