Cyclic stress—strain response of two-phase alloys Part I. Microstructures containing particles penetrable by dislocations

Abstract

Specimens of solution-treated Al-4% Cu alloy and aged alloy with coherent θ″ precipitates have been cycled under constant plastic strain over a wide range of fatigue life. The cyclic hardening and subsequent softening which occurs have been investigated by phenomenological experiments, electron and scanning microscopy and by optical microscopy. Hardening is interpreted by unidirectional concepts and softening by a disordering hypothesis, a new application with respect to fatigue. On the basis of these results, a general interpretation of cyclic response in this type of two-phase alloy has been obtained.