Effect of Secondary Processing and Nanoscale Reinforcement on the Mechanical Properties of Al-TiC Composites

Abstract

Aluminium based composites containing 1, 1.5 and 2wt. % of nano-sized Titanium Carbide particulates (TiC), with an average of 45nm, reinforcement were synthesized using low energy planetary ball mill followed by hot extrusion. Microstructural characterization of the materials revealed uniform distribution of reinforcement, grain refinement and the presence of minimal porosity. Properties characterization revealed that the presence of nano-TiC particulates led to an increase in hardness, elastic modulus, 0.2% yield strength (0.2% offset on a stress-strain curve), and the stress at which a material exhibits a specified permanent deformation, Ultimate Tensile Strength (UTS) and ductility of pure aluminum. Fractography studies revealed that the fracture of pure aluminum occurred in ductile mode due to the incorporation and uniform distribution of nano-TiC particulates. An attempt is made in the present study to correlate the effect of nano-sized TiC particulates as reinforcement and processing type with the micro structural and tensile properties of aluminum composites. The mechanical properties, namely, the UTS, hardness, grain size and distribution of the reinforcement in the base metal were studied in as sintered and extruded conditions. Orowan strengthening criteria was used to predict the yield strength of Al-TiC composites in the present work and experimental results were compared with the theoretical results.