Evolution of Microstructure in Eutectic Al-Si Alloys

摘要

In the present paper, the combined grain refinement and modification effects on the morphology of α-Al dendrites and on the eutectic Si respectively have been investigated in Al-12Si and LM-6 alloys. Indigenously developed Al-1Ti-3B (M13) and Al-5Ti-1B (M51) master alloys were used as grain refiner and Sr was used as a modifier. In addition, influence of various addition levels of Mg was studied individually and in combination with M13 master alloy on Al-12Si alloy. The results suggest that, addition ofMg can counteract the poisoning effect of Si in Al-12Si alloy. Results also suggest that, both refinement of α-Al (elongated to equiaxed dendrites) and modification of eutectic Si (elongated plates to fine particles) are possible in Al-12Si and LM-6 alloys when combined addition of grain refiner and modifier are made to the melt and resulting in improved mechanical properties.