Disconnection motion along (10
12) and (11
21) twins in Zr is investigated
using atomic-scale simulation. In particular, the high mobility of glissile disconnections
is studied in terms of the atomic shears and shuffles involved.
Using a quasi-static simulation procedure, the displacements of individual
atoms are followed as they transit from matrix sites, through interfacial sites,
and hence to twin sites by repeated passages of disconnections along the interface.
It is found that the overall displacements for the cases studied are those
predicted by the Bilby and Crocker (1965) theory which invokes homogeneous
shear deformation. However, the present work enables atomic tracks to
be followed through the cores of moving disconnections. The combinations of
shears and shuffles in the two twinning systems are found to be quite distinct.
In addition to tracking their coordinates, the variation of hydrostatic pressure
experienced by the atoms is also quantified.