Abstract
High angle (001) twist boundaries have been frequently 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 of these boundaries neither localised gbd's nor distinct energy cusps have been identified. The principal aim of the present study is to clarify this discrepancy between observations and computer modelling. For this urpose the structure and energy of a number of long period (high ∑) twist boundaries with misorientations very close to ∑ = 5 have been calculated using empirical pair and n-body potentials to describe interatomic forces. Furthermore, an isolated gbd embedded into a ∑ = 5 boundary has been modelled. Well defined cusps at ∑ = 5 misorientation and localised gbd's have been found but the reference ∑ = 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 a Read-Shockley type model. The cusps are always very shallow and may have an uncoventional 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.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call