DEVELOPMENT OF NANO-FIBROUS EUTECTIC AND PRIMARY SILICON PHASES IN Al-SI CAST ALLOYS FOR HIGH STRENGTH STRUCTURAL APPLICATIONS

Among the high strength lightweight materials, hypereutectic Al-Si cast alloys with constituent phases that possess nano-scale dimensions are highly desirable for automotive and aerospace applications. Recently, we have achieved ultra-high strength Al-Si alloys via directional solidification technology. In these directionally solidified alloys, both the eutectic and primary silicon phases have nano-sized fibrous morphologies. This paper describes the microstructure evolution and manufacturing of these advanced alloys and introduces ways of implementing these findings of directionally solidified casting into near-net shaped castings.