Dislocation Structures in Fatigued CuZn Single Crystals

Dislocation structures in CuZn alloy single crystals were examined by means of transmission electron microscopy. The overall dislocation structure, typical for the whole volume of fatigued crystals, strongly depends on the degree of difficulty of cross slip. In crystals with sufficiently easy cross slip the surface extrusions and intrusions were found to be related to the persistent slip band structure, differing from that in the remaining volume, while in crystals with very difficult cross slip no persistent slip bands lying under the surface relief were found. Further, the role of the persistent slip bands in fatigue process is discussed.