Final report: Aluminium based Nanoeutectics: Synthesis and Microstructure

Abstract: The primary aim of the project was to explore the possibility of synthesising high strength multiphase eutectic alloys based on aluminium which also exhibits reasonable ductility. The approach used was to develop a multiscale microstructure including nanometer length scale eutectic colony using ternary alloys and evaluate their deformation behaviour. We have carried out work on two alloy systems, Al-Cu-Si and Al-Fe-Ni. Both exhibit ternary eutectic reaction. The microstructures were manipulated by imparting high cooling rates during solidification. In case of Al -Cu-Si system, we are successful in obtaining a dual length scale microstructure in the nanometric range. In a Al81Cu13Si6 alloy, this has resulted in a material whose strength exceeds 1 GPa with 11% plastic strain. In the case of Al-Fe-Ni system, the ternary nanoeutectic ( Al 3 at % Ni 0.3at% Fe) produced by very high rate of solidification yielded moderate strength (260MPa ) with 12% ductility. However, even at 300C, the composite shows a yield strength of 170MPa.These results indicate that nanostructuring of the eutectic structure can yield a new class of materials with good high temperature strength.