On the measurement of relative translations between adjacent crystals

Abstract

A technique using a transmission electron microscope was recently used to study the structure of a twin interface in b.c.c. Fe 3% Si by establishing the relative translation of the adjacent crystals. The purpose of this note is to point out that this technique has been used extensively in previous work to study the structure of interfaces in f.c.c. metals, and the dislocations which are found there. It is emphasized that the image contrast observed using this technique can only be simply interpreted provided certain diffraction conditions obtain. Also, the possibility of a small magnitude translation perpendicular to the boundary in b.c.c. twins is discussed.