On the Structure of Tilt Grain Boundaries in Cubic Metals. III. Generalizations of the Structural Study and Implications for the Properties of Grain Boundaries

摘要: The results of atomistic calculations long-period tilt boundaries, which were reported in the preceding parts I and II, are generalized represented concisely by using two-dimensional lattices, called decomposition lattices. basis vectors a lattice characterize two fundamental structural elements composing all boundaries continuous series boundary structures. Conversely, governing condition on is that structure can change continuously throughout misorientation range between vectors. On assuming no discontinuous changes occur at non-favoured orientations, considered stable with respect to faceting, may be used deduce selection rules for adjacent favoured existence other given boundaries. necessary possible orientation formulated. Various aspects intrinsic extrinsic grain dislocations (g.b.ds) treated. It first shown observation g.b.d. networks transmission electron microscope does not necessarily imply reference structure, preserved those g.b.ds, boundary. Secondly, it argued g.b.ds provide imperfect steps Burgers vector components parallel do exist equilibrium high-angle Finally, an explanation physical plane matching proposed. A general classification properties introduced based this investigation structure. only properties, such as diffusion, depend exclusively atomic core detect Favoured misorientations where property but its derivative, misorientation, not. Grain energy against relation sliding migration then discussed.