Direct observation of zonal dislocation in complex materials by atomic-resolution scanning transmission electron microscopy

Dislocation glide to carry plastic deformation in simple metals and alloys is a well-understood process, but the process in materials with complex crystal structures is not yet understood completely as it can be very complicated often involving multiple atomic planes during dislocation glide. The zonal dislocation is one of the examples predicted to operate in complex materials, and during glide it involves multiple atomic planes called shear zone, in which non-uniform atom shuffling occurs. We report direct observation made by Z-contrast atomic-resolution microscopy of the zonal dislocation in the σ phase FeCr. The result confirms the zonal dislocation indeed operates in this material. Knowledge gained on the dislocation core structure will lead to improved understanding of deformation mechanisms in this and other complex crystal structures and provide ways to improve the brittleness of these complex materials.