Microstructure, Corrosion and Mechanical Properties of TiC Particles/Al-5Mg Composite Fillers for Tungsten Arc Welding of 5083 Aluminum Alloy

A semi-solid stir casting mixed multi-pass rolling process was successfully employed to manufacture TiCp/Al-5Mg composite filler wires with different contents of TiC particles. The 5083-H116 aluminum alloys were joined by tungsten inert gas (TIG) using TiCp/Al-5Mg composite weld wires. The microstructure, mechanical properties, fractography and corrosion behavior of the welds were evaluated. The results revealed that TiC particles were distributed in the welds uniformly and effectively refined the primary α-Al grains. The hardness and tensile strength of the welds were improved by increasing the TiC particle content, which could be attributed to the homogeneous distribution of TiC particles and the microstructure in the weld joints. Potentiodynamic polarization testing revealed that the corrosion resistance of the welds also increased with the addition of TiC particle contents. In addition, the stress corrosion cracking (SCC) susceptibility of the welds decreased as micro-TiC particles were introduced into the welds. The electronic structure of the Al/TiC interface was investigated by first principle calculation. The calculation showed that valence electrons tended to be localized in the region of the TiC-Al interface, corresponding to an addition of the overall work function, which hinders the participation of electrons in the composite in corrosion reactions.