Effects of Alloying Elements on the Multiplication and Motion of Dislocations during High-Temperature Deformation in Solid-Solution Copper Alloys

Pure copper and Cu-30 mass% Zn (Cu-Zn) alloy were subjected to tensile deformation at room temperature (approximately 298 K) and 573 K. Dislocation multiplication and motion during deformation were analyzed using neutron diffraction line-profile analysis. For the pure copper specimens, the dislocation density during deformation at 573 K was lower than that at room temperature. In contrast, the Cu-Zn alloys exhibited comparable levels of dislocation multiplication at both temperatures. Line-profile analysis revealed that the crystallites in the pure copper specimens became finer as the dislocation density increased, while the crystallite size of the Cu-Zn alloy specimens deformed at 573 K was considerably large and beyond the range that can be evaluated by the line-profile analysis. In the Cu-Zn alloys, although the dislocation density at 573 K was comparable to that at room temperature, the texture evolved by dislocation motion was weakened at 573 K, suggesting suppressed dislocation motion under these conditions. Transmission electron microscopy observations further demonstrated distinct dislocation substructures in the Cu-Zn alloys deformed at room temperature and 573 K. At room temperature, a Taylor lattice structure was observed, characterized by dislocations accumulating on planar slip planes. In contrast, at 573 K, dislocations were randomly distributed in a wavy form without forming tangles. This behavior suggests that the mobility of dislocations is reduced owing to interactions between solid solution elements and dislocations in the Cu-Zn alloys at 573 K.