Electron microscopic observations on the structure of dislocations in interphase boundaries

Abstract

The misfit dislocation structure of interface boundaries between α-brass (f.c.c. structure) and β-brass crystals (b.c.c. structure) was investigated by transmission electron microscopy to test the dislocation model of incoherent interfaces. It was observed that a variation of one degree or less of the misorientation between neighbouring α/β-brass crystals may result in the invisibility of the misfit dislocations. This observation seems to be at variance with the predictions of the misfit dislocation model and suggests a change of the misfit dislocation core structure in the sense that the width of the misfit dislocation cores increases so rapidly with increasing deviation from the low energy orientation relationship that the cores overlap and the misfit dislocation model may be of limited physical significance.