Low Cycle Fatigue Properties of Al-Si Eutectic Alloys

The effect of Si-phase on the axial, low-cycle fatigue behavior of Al-Si eutectic alloys was investigated using test specimens prepared from alloys processed either by continuous casting or extrusion. Results indicate that, for continuous casting, all fatigue fractures resulted from shear-type crack initiation and propagation with an attendant shortening of fatigue life. For extruded material, fatigue cracks originated in the Si phase. In both instances, initiation and growth mechanisms were essentially identical to those observed in high-cycle fatigue. Cyclic properties obtained from phenomenological models are presented and discussed.