Dislocation structure and energy of high angle (001) twist boundaries: A computer simulation study
Abstract
High angle (001) twist boundaries have been investigated experimentally and the presence of grain boundary dislocations (GBD's) and associated cusps in the dependence of the boundary energy on misorientation, is in this case well established. However, in previous computer simulations neither localized GBD's nor distinct energy cusps have been identified. The aim of this study is to clarify this discrepancy between observations and computer modelling. For this purpose the structure and energy of a number of long period (high Sigma) twist boundaries with misorientations very close to Sigma - 5 have been calculated using empirical pair and n-body potentials to describe interatomic forces. Furthermore, an isolated GBD embedded into a Sigma - 5 boundary has been modeled. Well-defined cusps at Sigma - 5 misorientation and localized GBD's have been found but the reference Sigma - 5 structure is always the lowest energy structure which, in general, does not possess the symmetry of the coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using a Read-Shockley type model. The cusps are always very shallow and may have an unconventional shape which is related to the dependence of the elastic energy on misorientation that is not the same for twist and tilt boundaries, contrary to what is usually assumed. Finally, some remaining discrepancies between observed types of GBD's and those found in the present study are discussed in the light of the previously proposed multiplicities of boundary structures.
- Publication:
-
Unknown
- Pub Date:
- June 1987
- Bibcode:
- 1987dseh.rept.....S
- Keywords:
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- Computerized Simulation;
- Grain Boundaries;
- Twisting;
- Copper;
- Gold;
- Metals;
- Solid-State Physics