Abstract
Aluminium alloy 5083 plates were joined using friction stir welding (FSW) technique individually or in combination with boron carbide (B4C) and carbon nanotubes (CNTs). The effect of these reinforcements on mechanical properties, microstructure evolution and corrosion behaviour after FSW has been investigated. Radiography confirmed good fusion in the welded zone and the absence of surface or subsurface defects. The tensile testing results indicated a 35% decrease in tensile strength after FSW of the Al-5083 plates compared to the base metal, but it increased once again after the addition of individual reinforcements of B4C and CNTs due to grain refinement and second phase strengthening. In the sample with hybrid reinforcement, premature failure was observed due to lack of fusion and improper bonding between the two reinforcing materials. A similar trend was observed in the case of flexural testing. Severe plastic deformation and reduced grain size increased the micro-Vickers' hardness values of reinforced samples. Evolution of the aluminium grain structure was analyzed using optical and stereo microscopy, while uniform dispersion of reinforcements and chemical composition was characterised by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. Increase in corrosion resistance was also observed after FSW and addition of reinforcements.