The porosity formation in relation to the feeding behavior of aluminum-silicon alloys has been widely studied because porosity is often the cause of the degraded mechanical properties of the castings. However, the effects of silicon content and melt treatments on the feedability of Al-Si alloys have not been adequately understood. Furthermore, in most prior studies air melting was employed, so that a substantial amount of dissolved hydrogen could remain in the melt even after degassing. In this case, the true feeding behavior could not be determined due to the dominant effect of hydrogen evolution during solidification. Therefore, in this study, an attempt was made to minimize the effect of hydrogen by melting, degassing, and pouring in vacuum. And in this manner, the feedability of Al-Si alloys was investigated.; In this research, the optimum feedability of Al-Si hypoeutectic alloys was determined for alloys with a silicon content of about 4%. The feeding capability of Al-Si alloys was found to be significantly affected by the solidification mechanism of both the proeutectic dendrites and the eutectic grains. The feedability of Al-Si alloys was greatly improved by both Sr-modification of the eutectic and alpha grain refinement. Feedability of hypereutectic Al-Si alloys was compared with hypoeutectic alloys in order to evaluate the effect of the proeutectic phase. Almost no porosity was found in the hypereutectic Al-Si alloys.; The interaction between pores and an advancing interface is an important phenomenon affecting the final pore distribution in castings. Therefore, a unidirectionally solidified alloy was quenched during solidification to investigate the behavior of pores at the solid/liquid interface. A pore behavior map was developed to explain the pore/interface interaction by modifying a particle behavior map developed elsewhere, and was generally validated by the obtained experimental results.
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