Effect of Rare Earth Metals on Porosity Formation in A356 Alloy

摘要

Abstract The present study was performed on A356 alloy containing various amounts of La, Ce or La?+?Ce, without and with about 80–100?ppm Sr. The main objective was to evaluate the porosity formed in rare earth metals (RE) containing Al–Si cast alloys. The results reveal that the addition of large amounts of RE (approximately 3%) would cause a marked increase in the freezing zone coupled with a marked volume fraction of RE-based intermetallics which would reduce the alloy feedability, leading to the formation of a significant percentage of shrinkage porosity. This situation is more severe in Sr-treated alloys. The depression in the eutectic Si temperature is not necessarily a parameter to consider in determining the degree of eutectic modification. Cerium is relatively more effective than La in terms of porosity formation.