Influence of natural and artificial aging on the mechanical properties of high-pressure die casted (HPDC) AlSi9Cu3(Fe)/MWCNT nanocomposite

Abstract This study investigates the influence of multiwalled carbon nanotubes (MWCNT), as reinforcement in the AlSi9Cu3(Fe) matrix, for production of metal nanocomposite material. AlSi9Cu3(Fe) alloy found special application in the automotive industry using high pressure die casting (HPDC) process. The main goal of the experiment was development of a nanocomposite material that can achieve significant decrease in the vehicle mass, which will have a positive impact on fuel consumption and general CO 2 emission into the atmosphere. Three different states of nanocomposite material were investigated: casted, naturally, and artificially aged. The produced nanocomposite was analyzed using an optical emission spectrometer and carbon–sulfur (CS) elemental analyzer to determine the chemical composition and presence of MWCNT. Tensile strength testing was carried out on the universal static testing machine, and both optical and scanning electron microscopy were used for microstructure analyses, followed by energy-dispersive X-ray spectroscopy (EDS) analysis of main microstructural constituents. A significant increase in tensile strength after 3 years of the natural aging process is caused by precipitation hardening and the occurrence of a great number of extracted small intermetallic precipitates and a more homogeneous distribution of MWCNT in the metal matrix. The heat treatment for artificial aging process has shown an insignificant increase in tensile strength in comparison with the natural aging process.