Defect Susceptibility of Tensile Properties to Microporosity Variation in As-Cast Al–xSi Alloys

The defect susceptibility of tensile properties to microporosity variation in as-cast Al–xSi (x = 2, 5, 8, 11) binary alloys was investigated in relation to the effective void area fraction, which includes the area fraction and the size distribution of the pre-existing micro-voids and damaged eutectic Si particles. The area fraction of eutectic Si particles and Si colonies increases with increasing nominal Si content, and the typical morphology of micro-voids changes from shrinkage hole type to blow hole type as the Si content increases. The tensile properties of Al–xSi alloys depend on microstructural characteristics, including the nominal area fraction of eutectic Si particles and eutectic Si colonies, the width of the pro-eutectic Al matrix, and the variation in microporosity. The defect susceptibility of ultimate tensile strength and elongation is estimated by the nominal area fraction of eutectic Si colonies rather than the nominal Si content. The relative contribution of the eutectic Si particles to the effective void area fraction can be described using a modified constitutive model that may confirm that the damage evolution of the eutectic Si particles influences the tensile properties of Al–xSi alloys.