Atomic structure of a tilt grain boundary in a molybdenum bicrystal studied by 400 kV high-resolution electron microscopy

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Abstract
High-resolution electron microscopy of metals is now possible with the same accuracy as in [011] semiconductors, by means of the new electron microscopes working at higher accelerating voltage (400 kV). Molybdenum bicrystals have been elaborated and observed, with a misorientation angle in the range between low- and high-angle boundaries. The particular boundary can be described using either Σ = 41 or Σ = 25 references, so that structural units of these two coincidences are found experimentally. Atomic steps are also present and the associated Burgers vector and height are determined in the DSC lattice. A comparison between experimental and calculated images shows that the core of the dislocations is consistent with the model of a capped triangular prism, although some small differences are observed. The possible cause of such differences is attributed to impurity segregation.