Study of the Effect of Strontium (Sr) on the Nucleation of Eutectic Silicon (Si) in High Purity Hypoeutectic Al-5Si Alloys

摘要

High purity Al-5Si (wt. %) master alloys containing different levels of Sr additions were manufactured in an arc melter under high vacuum. The alloys were melt-spun which resulted in the production of thin ribbons. The microstructure of the ribbons consisted of Al matrix and entrained eutectic droplets. The ribbons were subsequently investigated using differential scanning calorimetry (DSC) and conventional transmission electron microscopy (CTEM) to examine the effect of Sr on the droplet undercooling and nucleation of eutectic silicon. The results indicate that the addition of Sr increases the eutectic droplet nucleation undercooling (AT). This may be due to Sr poisoning of the AIP phase.