Enhanced fatigue crack propagation resistance of an Al–Cu–Mg alloy by artificial aging under influence of electrical field

The combining effect of artificial age plus electric field (16 kV/cm) at 190 °C on microstructure and fatigue crack propagation (FCP) resistance of an Al–Cu–Mg alloy was investigated by transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and fatigue testing. The results showed that, during aging process with electric field grain boundaries became coarse with S′ phase precipitates, and the precipitates were much finer and dispersed more uniform in matrix. As a result, tensile properties of aged samples did not change significantly. FCP resistance of samples with electric field on was higher due to higher barriers for dislocation movement, caused by more dispersed precipitates of S′ phase. A vacancy-atom diffusion model was introduced to explain microstructure evolution during electric field aging process.