The generated results on superplastic flow (SPF) in materials produced by severe plastic deformation (SePD) have been analyzed. Formation of sliding surfaces with subsequent cooperative grain boundary sliding (CGBS) has been demonstrated to be a main deformation mechanism of superplasticity under conditions of microstructural stability. A substantial role of dislocation glide in accommodation processes is shown. When grain growth is observed during deformation, continuous grain boundary migration prevents formation of slide surfaces and CGBS is restrained. In this case, deformation of the material is more likely to occur by dislocation or diffusion creep than true SPF despite relatively large strains being reached.
Bibliographical noteFunding Information:
This material is based upon work supported by National Science Foundation under Grant No. NSF-DMR-0240144 and the National Center for Electron Microscopy (NCEM) at Lawrence Berkeley laboratory (proposal #257 for electron microscopy support).
- Plastic behavior
- Severe plastic deformation