COMPUTED STRUCTURE OF NEAR-COHERENT TWIN BOUNDARIES COMPARED WITH TEM OBSERVATIONS

The structure of a near-coherent twin boundary in a Au bicrystal was investigated. Upon annealing, a low angle boundary and a parallel coherent twin boundary merged to form a near-coherent twin boundary with a deviation of 0. 45 degree from the exact twin orientation. In the near-coherent twin boundary a dislocation network has been observed with a characteristic six-star pattern. In an effort to reproduce these patterns in a computer simulation study, the atomic configurations in (111) twist boundaries close to the twin orientation were calculated ( SIGMA 37, SIGMA 61, SIGMA 91, SIGMA 127, SIGMA 169). For a given twist boundary and interatomic potential, both patterns were obtained. The triangular structure appeared energetically much more favorable, independent of the various interatomic potentials employed.