Effect of Self-Inoculation Treatment on Microstructure and Mechanical Properties of Eutectic Al-Si Alloy

Eutectic Al-Si alloy was self-inoculated by spheroidized Al-12.6Si alloy. The microstructure and mechanical properties of self-inoculated eutectic Al-Si alloy were observed by optical microscopy, scanning electron microscopy, and the universal tensile testing machine. The results show that the area fraction of alpha-Al phase in eutectic Al-Si alloy increased first and then decreased with an increase in the added amount of the inoculant at 700 degrees C. When the added amount of inoculant was 0.4 wt %, the area fraction of the alpha-Al phase in the eutectic Al-Si alloy also increased first (to a maximum of 30.9%) and then decreased with increasing temperature. Also the eutectic silicon transformed from coarse needle flakes into fine particles as inoculant was added. And when the added amount of inoculant was 0.4 wt %, the tensile strength and elongation of the alloy reached maximum values and the tensile fracture of the alloy showed ductile fracture characteristics. Therefore, the self-inoculation treatment is an effective method to improve the mechanical properties of eutectic Al-Si alloys.