Abstract
Effects of aging at 473 K on the relationship between microstructure and fatigue strength for an Al–4%Ge alloy has been investigated. The fatigue strength is lowered with increasing aging time. The fatigue life is deduced to be greatly affected by the initiation of the crack since the present fatigue test condition is in a high-cycle range. The crack is likely to initiate at the coarse precipitate located at the intersection between the free surface and grain boundary. This mechanism can explain the reduction in fatigue strength with increasing aging time, that is, with the increase in the size of the coarse precipitate.
