Dislocation cells in additively manufactured metallic alloys characterized by electron backscatter diffraction pattern sharpness

Metallic alloys produced by additive manufacturing often host complex and hierarchical microstructures with grains exhibiting large orientation gradients, along with sub-grain dislocation cells. These multiscale features act in concert to control mechanical behavior, yet are challenging to characterize at high fidelity over large areas. Here, we quantify the sharpness of electron backscatter diffraction patterns obtained from several additively manufactured metallic alloys to directly image the dislocation cells at the mesoscale in bulk materials. The sharpness metric employed herein reflects the elastic strain field from dislocations, and exhibits unique advantages, including being proportional to local dislocation density, insensitive to grain orientation, and inherently correlated with orientation mapping and its related modalities. Our results demonstrate that the cell walls do not always possess appreciable misorientations, and thus do not always contain large fractions of geometrically necessary dislocations, thereby furthering our understanding of the origin and implications of the profuse dislocation cells produced during additive manufacturing.

Automated summary

Metallic alloys produced by additive manufacturing often have complex microstructures, including orientation gradients and dislocation cells. This study focuses on characterizing these features using electron backscatter diffraction patterns. The sharpness metric employed in this study reflects the elastic strain field from dislocations and exhibits advantages such as being proportional to local dislocation density and insensitive to grain orientation. The results contribute to our understanding of the origin and implications of the dislocation cells produced during additive manufacturing.