  We introduce a method to visualize dislocations along grain boundaries at the
atomic level. It uses an atomic-level Nye tensor, representing the dislocation
density. To calculate the Nye tensor at grain boundaries, we extend the
Hartley-Mishin strain gradient calculation to the displacement shift complete
lattice. We show that the method is effective in visualizing disconnections and
the dislocation content of grain boundary phase junctions in body-centered
cubic tungsten, as well as face-centered cubic copper. In addition, we use the
method to characterize the morphology of a two-dimensional grain boundary phase
nucleus in a symmetric tilt grain boundary in tungsten. This method can be
applied to both bulk dislocations and grain boundary disconnections, which
makes it ideal for studying the interactions and reactions of bulk dislocations
with grain boundaries, and grain boundary disconnections.
