Novel method of nanoparticle addition for friction stir welding of aluminium alloy

Abstract

2.5 mm thick 6061-T6 aluminium alloy sheets with nanoparticles addition at abutting edges were joined using Friction Stir Welding (FSW). This study aims to investigate the effect of novel nanoparticles’ addition strategy on the nanoparticle distribution for metallurgical and mechanical properties of weldments. The nanoparticle dispersion in different FSW zones were analysed using optical and SEM micrographs. The Vickers microhardness tests were conducted with more emphasis on the nugget zone (NZ). The outcomes were correlated with the grain size, nanoparticle dispersion, and their effect on metal-matrix. Results revealed that the surface appearances of welds with Al2O3 nanoparticles are smooth well forged compared to the TiO2 weld that has rough surface with the flash formation on both sides of NZ. The microstructural study revealed the more refined NZ grain structure for Al2O3 welds due to homogenous nanoparticles dispersion than TiO2 nanoparticles welds in which clusters formation in the NZ leads to increases the grain size that results in non-uniform nanoparticles distribution. The NZ microhardness of Al2O3 nanoparticles welds (88Hv) was significantly higher than TiO2 welds (76Hv) and base material (61Hv) due to grain refinement and uniform nanoparticles distribution in the NZ.