Molecular dynamics study of dislocation-twin boundary interaction in titanium subjected to scratching

Abstract

The interaction mechanisms of dislocations generated during scratching of titanium crystallites with a Ʃ11b incoherent twin boundary (ITB) and a general grain boundary (GB) were studied using molecular dynamics simulations. The interaction of dislocations with the ITB was shown to result in strengthening its barrier properties due to disordering of atomic structure and nanofragmentation of the material in the areas adjacent to the ITB as well as to ITB migration. Comparative study of the ITB and GB, which are characterized by similar initial energies and atomic order, revealed that in both the cases the interaction of dislocations with the boundaries gives rise to the similar atomic disorder. The results obtained indicate that it is the crystallographic misorientation of the adjacent crystallites, which implies the orientation difference across the boundary and the absence of mutual nodes of the crystal lattices, that determines stronger barrier properties of the GB as compared with the ITB.