Cyclic stress—strain response of two-phase alloys Part II. Particles not penetrated by dislocations

Abstract

Specimens of Al-4% Cu alloy with microstructures containing θ′ precipitates were cycled under constant plastic strain over a wide range of fatigue life. Cyclic response (hardening and saturation) was investigated by phenomenological experiments and by transmission and scanning microscopy. Applying unidirectional hardening mechanisms, we determined how the second phase controlled the cyclic response when the precipitates were closely spaced; and how the cyclic response approached that of single phase materials, when the interparticle spacing was equal to or greater than the self trapping distance of dislocations.