Study of Refinement and Morphology Change of AlFeSi Phase in A380 Alloy due to Addition of Ca, Sr/ Ca, Mn and Mn, Sr

Abstract

While aluminum-silicon (Al-Si) alloys are one of the most versatile aluminum alloys, iron is considered one of the most harmful elements in Al-Si diecasting application. Its presence leads to the precipitation of many AlFeSi intermetallic phases and unacceptable mechanical properties, such as reduction in ductility. Thus controlling the fraction and morphology of the AlFeSi phase, especially the β-AlFeSi phase is an important way to improve the ductility of Al-Si die casting alloys. In this article, Ca/Mn, Ca/Sr and Sr/Mn elements were added into A380 alloys to study the effect of combined element addition on the morphology change of the AlFeSi phase. Sr and Ca addition can impair the modification effect and introduce sludge. Mn and Ca, Mn and Sr can result in a microstructure consisting of fcc α-Al, modified eutectic Si, α-AlFeSi Chinese script phases and a refined platelet β-phase. However, use of high cooling rates can better refine the morphology of the AlFeSi phase and lead to a better alloy product.