Cyclic deformation in Al4wt.%Cu alloy single crystals containing coherent θ″ precipitates I: Cyclic stress-strain response

Abstract

Push-pull fatigue testing on single crystals of binary Al−3.8wt.%Cu alloy containing coherent shearable θ″ precipitates has been carried out under constant plastic strain control and also under stress control. The cyclic responses associated with plastic resolved shear strains in the range 10 −6 10 −2 have been investigated. The effect of crystal orientation has also been explored. The cyclic stress-strain curve exhibits “tri-regional” behavior with a plateau extended over about two decades of strain. This curve has been correlated with the formation of persistent slip bands and a fatigue limit corresponding to the low strain end of the plateau. The orientation of the crystal has little effect on this behavior. In view of the many common features in the cyclic response of this alloy and that of pure metals and other alloys, we believe that the behavior reported here will be found general to alloys containing shearable precipitates.