DETERMINATION OF OPTIMUM Sr LEVEL FOR EUTECTIC Si MODIFICATION IN Al-Si CAST ALLOYS USING THERMAL ANALYSIS AND TENSILE PROPERTIES

This study presents a correlation between the depression in eutectic growth temperature as a result of Sr modification and the tensile properties of Al-Si cast alloys. In order to study the role that Sr exerts on the solidification behavior, modification and mechanical properties, controlled solidification experiments including thermal analysis were performed. Using three mold materials for different cooling rates, tensile testing was conducted on Al-Si alloys with various Sr levels (similar to 35-500 ppm). The gradient solidification technique was used to produce directionally solidified tensile test specimens containing low levels of defects. The depression in eutectic Si growth temperature was correlated with the Sr additions and the tensile properties (elongation to failure and tensile strength).