The formation of stable interstitial configurations in the (1121), (1122), (1011) and (1012) twin boundaries in hexagonal closed packed metals has been studied by computer simulation. The crystals have been modelled by either a pair potential for a crystal with a near-ideal c/a lattice parameter ratio or a many-body potential for titanium. These potentials have proved to be satisfactory for the simulation of both twin boundaries and point defects. It is found that the twin boundary gives rise to stable interstitial configurations exhibiting a high binding energy. These configurations are not found in the perfect lattice and are highly dependent on the twin crystallography. The variation of the twin-interstitial binding energy as a function of the defect distance to the interface depends also on the twin structure. The features are qualitatively the same for both potentials for the (1121) and (1122) twins, but differences between the two model potentials are observed for the (1011) and (1012) twin boundaries.
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