An investigation of the synthesis, consolidation and mechanical behaviour of Al 6061 nanocomposites reinforced by TiC via mechanical alloying

Abstract

Nanostructured Al 6061–xwt.% TiC (x=0.5, 1.0, 1.5 and 2.0wt.%) composites were synthesised by mechanical alloying with a milling time of 30h. The milled powders were consolidated by cold uniaxial compaction followed by sintering at various temperatures (723, 798 and 873K). The uniform distribution and dispersion of TiC particles in the Al 6061 matrix was confirmed by characterising these nanocomposite powders by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The mechanical properties, specifically the green compressive strength and hardness, were tested. A maximum hardness of 1180MPa was obtained for the Al 6061–2wt.% TiC nanocomposite sintered at 873K, which was approximately four times higher than that of the Al 6061 microcrystalline material. A maximum green compressive strength of 233MPa was obtained when 2wt.% TiC was added. The effect of reinforcement on the densification was studied and reported in terms of the relative density, sinterability, green compressive strength, compressibility and Vickers hardness of the nanocomposites. The compressibility curves of the developed nanocomposite powders were also plotted and investigated using the Heckel, Panelli and Ambrosio Filho and Ge equations.