Microstructural, mechanical and corrosion properties of aluminium MIG welds reinforced with copper powder

Metal matrix composites have been used in recent times to achieve better mechanical properties of materials and welded structures. Aluminium and its alloys provide unique properties which makes it one of the most attractive metallic, economical, versatile material for a broad range of uses in engineering applications, such as aerospace, automobile and mineral processing industries. Against this background, aluminium is not suitable for all engineering applications, and it sometimes requires some degree of reinforcement, particularly in a corrosive environment and/or at elevated temperatures. This study focuses on ascertaining the integrity of MIG welded AA1100 reinforced with copper powder at the weld zone. This was achieved through tensile testing, microhardness profiling and microstructural investigation via the scanning electron microscope, the energy-dispersive spectroscopy and optical microscope, followed by corrosion test by electrochemical polarization method. The results revealed that the addition of copper powder significantly increased the hardness property of the welds, as the welds with copper powder particle reinforcement showed higher hardness values when compared to those without the copper powder particle reinforcement. The highest tensile strength was obtained from the copper reinforced sample. Furhermore, the microstructures revealed finer grain structures for the reinforced samples. The samples with reinforcement also exhibited better corrosion properties. It was therefore concluded that the aluminium (Al) and copper (Cu) metal matrix composite welded via MIG welding produced better mechanical properties, as well as increased corrosion resistance behaviour, and it can definitely be recommended for typical applications.