Characterization of Extrinsic Grain-Boundary Dislocations and Grain-Boundary Dislocation Sources by Transmission Electron Microscopy. Final Report, June 1, 1979-May 31, 1981

摘要

The microstructures attendant to specific peak strains along the strain axis of the stress-strain diagram for type 304 stainless steel and nickel have been examined and compared by transmission electron microscopy from epsilon = 0.05% to 55% in the former and from epsilon = 0.05% to 35% in the latter. The onset of flow is characterized by the emission of dislocations from grain boundary ledge source which form emission profiles resembling dislocation pileups in the stainless steel, and a random distribution of dislocations with evidence for very short emission profiles near the grain boundaries in nickel. At the engineering yield point (0.2%) every grain in the stainless steel shows evidence for dislocation emission profiles, while in the nickel every grain contains some dislocations distributed within the grain interior. (ERA citation 06:023902)