Dislocations interact via their stress fields. They can attract or repel each other.

This interactive diagram shows the elastic stress field around an edge dislocation. Above the dislocation the stresses are compressive, whilst below they are tensile.

Click the cursor anywhere on diagram to introduce a second dislocation. Observe how the stress fields interact.

Keep clicking to move the second dislocation. See how the mean stress (arbitrary units) varies as its position relative to the central dislocation changes. Which configurations result in lower stresses? Which result in higher stresses?

You can also use the checkbox to toggle between dislocations of the same and opposite signs. Again, observe how the mean stress changes. If the opposite dislocations meet each other on the same slip plane, they cancel each other out, and the stress fields disappear.