Microstructural Stability and Fatigue Deformation in Cu and Al-0.7s at. % Mg Single Crystals

Abstract

Fatigue hardening and fatigue softening were studied by the constant plastic strain amplitude fatigue technique in copper and Al-0.7 at. % Mg single crystals. The defect morphology in the saturation stage was studied by transmission electron microscopy. The results show that a unique saturation stress characteristic of a given plastic strain amplitude exists for both materials. The cell boundaries consist of dislocations of the primary, conjugate, and critical slip systems after fatigue softening. The density of edge dipoles and of primary screw dislocations straddling the cells walls after fatigue softening is smaller than that observed after fatigue hardening. (Fatigue, Fatigue hardening, Fatigue softening, copper, Al-Mg).