The effect of strontium on the microstructure of the aluminium-silicon and aluminium-copper eutectics in the 319 aluminium alloy

Publisher Website
Google Scholar
Abstract
The influence of strontium on the silicon modification and aluminium-copper eutectic microstructures in the 319 aluminium alloy was examined. The strontium levels considered were between 8 and 96 ppm. The purpose of this study is: (i) to observe the effects of strontium on the degree of silicon modification in the 319 aluminium alloy, and (ii) to determine the effects of strontium level on the area fraction of copper phases. The degree of silicon modification was determined using the American Foundrymen's Society (AFS) specification. The area fractions of aluminium-copper phases were examined using scanning electron microscopy (SEM) and quantitative image analysis (IA). This investigation showed that a strontium level between 75 and 85 ppm was sufficient to modify the thermal analysis test sample's silicon structure to an AFS specification No. 4. Increasing the strontium level from 8 to 96 ppm leads to the larger area fraction of the interdendritic blocky Al2Cu eutectic structure and lower area fraction of the eutectic Al-Al2Cu structure with interspersed α-Al phase in the as-cast structure.