Development of novel Al-Si-Mg alloys with 8 to 17 Wt% Si and 2 to 4 Wt% Mg

A new family of Al alloys is being developed to obtain superior castability and properties of the cast component as compared to conventional Al-Si cast alloys. Alloys with compositional ranges varying from 8 wt% to 17 wt% Si coupled with 2 wt% to 4 wt% Mg are being investigated. These alloys were developed based on our understanding of the effect of various iron containing phases and Sr additions on the nucleation of the eutectic phases in Al-Si hypoeutectic alloys. Higher than conventional levels of Mg was added for two reasons. Firstly, to prevent the formation of β(Al,Fe,Si) intermetallic phase by promoting the formation of π(Al,Fe,Si,Mg) phase during solidification, and secondly, to alter the rheological properties of the alloy leading to better fluidity and mould filling characteristics of these alloys. In this paper, the mechanical properties and casting behavior of a few compositions in the above-mentioned ranges will be presented.