Combined FIM/TEM determination of the structure of an incoherent twin boundary in tungsten

The techniques of field ion microscopy and transmission electron microscopy have been used to investigate an incoherent twin boundary in tungsten in which a small (∼1°) twist misorientation is accommodated by a hexagonal network of screw dislocations. The Burgers vectors of the dislocations comprising the network have been determined to be of the type a/3(211), and it is shown that these correspond to those of the perfect grain boundary dislocations predicted by DSC lattice theory for this boundary. It is also demonstrated that if any rigid body translation is associated with the boundary, its magnitude is such that it is below the resolution of the FIM technique (<0.3 Å). © 1981 Taylor & Francis Group, LLC.