Etch-Pit Studies of the Dislocation Structures Developed during Creep Deformation of Copper Single Crystals

Abstract

Dislocation arrangements and substructure formation due to high-temperature creep deformation were investigated in copper single crystals by means of the etch-pit technique. Etch-pit observation was made on the surfaces parallel to the primary slip plane, (111), and to the critical slip plane, (\bar111).At an early stage of transient creep, in some regions, which will be called “region A”, subgrains elongating in the direction of the deformation band (10∼20μ×50∼200μ in size) were seen in the (111) observation. Cell structures (cell size : ∼100μ) were observed in the other regions, which will be called “region B”, adjacent to region A. Regions A and B were bordered along the plane of the deformation band, (\bar101). With the progress of transient creep deformation, the width of the long subgrains in region A increased and the cells in region B changed into well-developed subgrains, decreasing in their size. At the end of transient creep the width of the long subgrains in region A and the size of subgrains originating from the cell structures in region B were 20∼40μ and ∼50μ, respectively. The facts show that the structures in regions A and B tend to become similar with creep deformation. During steady-state creep, little change occurred in the shape and size of the substructures.Many primary dislocations were observed within the subgrains and the cells in transient creep. The primary dislocations, which were generated during instantaneous elongation, decreased in transient creep and increased slightly in steady-state creep.