Cellular dislocations: experiment and modeling

The concept of cellular dislocations (CDs) as topological defects in a regular grain array has previously been used as a convenient analogy with regular dislocations for modeling of deformation and grain growth processes on the scale of grain groups. This work provides experimental evidence supporting the existence of CDs. Results of observations of deformation relief at the surface of superplastically deformed samples under different strain states, distortion of marker lines due to grain group sliding, and in situ scanning electron microscope (SEM) deformation are provided. These data can be interpreted in terms of CDs. Finite element modeling (FEM) of sliding of grain groups indicates that stresses and strain are localized within a two grain size around CD.