THE DETERMINATION AND IMAGING OF CRYSTALLOGRAPHIC TEXTURE USING ELECTRON BACKSCATTER DIFFRACTION. D.J. Dingley, TexSEM Laboratories, Provo, Utah and The University of Bristol, UK

A system has been developed whereby Backscatter Kikuchi Diffraction patterns obtained from bulk samples in the scanning electron microscope can be automatically indexed enabling different crystallographic phases to be distinguished and crystal orientation measured. Such data collected at points spaced over a regular grid on a specimen surface permit the spatial distribution of these crystallographic features to be mapped on micrographical form. The technique is known as Orientation Imaging Microscopic and the maps as Orientation Image Micrographs. Interrogation of intercorrelations of grain size, phase and texture component. Mesotexture, i.e. The distribution of disorientations across grain boundaries can also be determined together with a measure of internal strain and the residual energy stored in dislocations clusters.

Results obtained from partially recrystallized steel illustrate the procedure and a typical analysis. The macroscopic texture was determined for the combined cold worked and recovered parts of the microstructure and compared with that pertaining to each fraction. The cold worked material was distinguished by it's characteristic deformation cell structure, whilst recovered material was taken to be that where the cell size was greater than that of the deformed material and had cell walls of less than five degrees disorientation across them. Recrystallized grains were taken as grains containing little substructure and surrounded by high angle boundaries.