Options for nanoreinforced cast Al–Si alloys with TiO2 nanoparticles

Abstract

This study presents a new concept of refining and enhancing the properties of cast aluminium alloys by adding nanoparticles. In this work the effect of adding titanium dioxide (TiO2) nano-particles (40 nm) to the aluminum cast alloy A356 as a base metal matrix was investigated. Titanium dioxide nano-powders were stirred into the A356 matrix with different fraction ratios ranging from (0, 1, 2, 3, 4, 5 %) by weight at variable stirring speeds ranging from (270, 800, 1500, 2150 rpm) in both the semisolid (600 °C) and liquid state (700 °C) using a constant stirring time of one minute. The cast microstructure exhibited change of grains from dendritic to spherical shape when increasing stirring speed. The fracture surface showed the presence of nanoparticles at the interdendritic spacing of the fracture surface and was confirmed with EDXS analysis of these particles. The results of the study showed that the mechanical properties (strength, elongation and hardness) for the nanoreinforced castings using TiO2 were enhanced for the castings made in the semi-solid state (600 °C) with 3 % weight% of TiO2 at 1500 rpm stirring speed.