Atomic-scale computer simulation was used to investigate the interaction of a moving {10•2} twin boundary in an hexagonal close-packed metal with either a straight 1/3{10•2}(00•1) dislocation lying perpendicular to the direction of twinning shear or a periodic row of perfect dislocation loops. The screw dislocation does not decompose in the moving interface and has no effect on its motion. The 60°-mixed dislocation was attracted by the boundary and decomposes into twinning dislocations and a disconnection (an interfacial defect with both step and dislocation character): the sign of the crystal dislocation determines the form of the disconnection and, thus, its effect on twin boundary motion. Boundary reactions with crystal dislocations were likely to be important for assisting the twinning process. Loops with Burgers vector, b, parallel to the interface were reformed in the other crystal after the twin boundary has passed through. The boundary attracts both interstitial and vacancy dislocation loops with inclined b, but was not transparent to them because the complete loop was swept along its glide prism by the moving interface. Depending on its nature, a loop either retains its structure in its parent crystal or was absorbed in the interface. The decomposition product in the latter case was consistent with the reactions of straight dislocations. The results indicate that twinning was efficient at sweeping loops from the microstructure when their density was low and was suppressed by loops when their density was high.

Interaction of a Moving {10¯12} Twin Boundary with Perfect Dislocations and Loops in a HCP Metal. A.Serra, D.J.Bacon: Philosophical Magazine, 2010, 90[7-8], 845-61