The analysis of burgers vectors of dislocations in coherent twin boundaries and other coincident site boundaries

Abstract

The Burgers vectors of dislocations forming a network in a coherent twin boundary (CTB) in an austenitie stainless steel were determined by transmission electron microscopy. An extension of Barry and Mahajan's (1971) method of diffraction contrast analysis, wherein lattice planes that are continuous across the CTB are oriented for two-beam diffracting conditions, was used to show that the Burgers vectors are of the type ±a/6〈112〉. It is also shown that dislocation contrast can be very weak, or absent entirely, when only one of the two crystals on either side of the CTB is diffracting strongly and g·b ≠ 0. Finally, it is demonstrated that the extended method of diffraction contrast analysis can be applied to the determination of Burgers vectors of grain boundary dislocations in coincident-site boundaries other than CTBs.