Mechanical properties of Spark Plasma Sintered Aluminium-Carbon Nanotubes composites

Abstract: A single material cannot meet the demand of advanced materials; this has contributed in production of composites. Pure aluminium (Al) is soft with moderate strength and young’s modulus, however properties such as low density and corrosion resistance has attributed to intense interest it has attracted. For pure aluminium to comply with mechanical properties that are required in different engineering applications, its mechanical properties have to be enhanced. Alloying elements, Solid solution strengthening, strain hardening and precipitation hardening have been used to enhance mechanical properties of Al alloys. This work presents the preparation, characterisation, spark plasma sintering (SPS) and evaluation of aluminiummulti walled carbon nanotubes (Al-MWCNTs) composites’ mechanical properties. Low energy ball millings (LEBM) were used to disperse up to 1.5 wt. % MWCNTs into Al matrix (0.5wt. % MWCNTs, 1wt. % MWCNTs and 1.5 wt. % MWCNTs were dispersed into Al matrix). Milled Al-MWCNTs powders composites and sintered Al-MWCNTs composites were characterised using optical microscopy (OP), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). OP was used to investigate the effect of MWCNTs on the microstructure of Al-MWCNTs composites, SEM and TEM were used to study morphology of MWCNTs, XRD was used for phase identification and Raman spectroscopy was used for structural integrity investigation. Microstructural characterizations of Al-MWCNTs composites reveal that the homogeneous dispersion of MWCNTs was achieved, MWCNTs were well embedded in the Al matrix, no agglomeration and small amount of aluminium carbide were observed. The effects of MWCNTs on the mechanical properties were studied using ultra nanoindenter tester. It is concluded that the incorporation of MWCNTs into Al matrix results in the increase in elasticity, plasticity, hardness, yield strength, modulus of elasticity, stiffness and strain rate sensitivity of aluminium composites. The enhancements of 55% in hardness, 55% in yield strength, 81% in modulus of elasticity, 89% stiffness and 20% in strain rate sensitivity compared to pure Al were observed.M.Tech. (Mettalurgy