EFFECT OF STRONTIUM ON VISCOSITY AND LIQUID STRUCTURE OF Al-Si EUTECTIC ALLOYS

摘要

This study aims to present conclusive evidence that trace level addition of Sr in Al-Si hypoeutectic alloys change the liquid melt characteristics and alter the nucleation environment of the eutectic phases. High temperature rheological experiments measuring viscosity of Al-Si eutectic melt with and without Sr addition show that Sr significantly alters the melt viscosities at various shear rate regimes. Further, liquid diffraction experiments have been carried out on Al-12.5wt%Si (eutectic) alloy using high-energy synchrotron X-ray beam source to determine the effect of Sr on various liquid structure parameters such as structure factor, pair distribution function and coordination numbers at various melt superheat temperatures. The analysis of the data suggests that Sr changes the nucleation environment of the eutectic Si phase. Further, the effect of Sr on the atomic arrangement of the Si atom with respect of Si and Al atoms in the liquid will be quantified and presented.