Abstract
The interaction of a moving {1012} twin boundary (TB) with clusters of self-interstitial atoms and vacancies, containing up to 35 point defects, has been studied by atomic computer simulation in a model crystal of hcp Zr. Conservative movement of the boundary has been achieved by glide of twinning dislocations under applied shear stress. Several reactions were observed, the result depending on cluster orientation and location relative to the glide plane of the twinning dislocation, i.e. tension or compression region. They included 1) restriction of TB mobility; 2) change of cluster orientation and shape; 3) glissile cluster drag by the TB without contact; and 4) total or partial absorption of a cluster by the TB and cluster drag, together with simultaneous glide along the TB. It is concluded that the applied shear stress for motion of TBs is raised by interaction with point defect clusters. Furthermore, moving TBs act as defect sinks or recombination centres and provide a means for removing defects from regions of radiation damage.
