Novel Fillers Reinforced with Nanoparticles for Aluminum TIG Welding

Andres Felipe Calle
University of Puerto Rico at Mayag├╝ez, Puerto Rico, United States

Keywords: TIG welding fillers, aerospace structures, nanocomposites

he defense and aerospace industries have increased the development of major structural components fabricated entirely from lightweight alloys. Alas, aluminum welding presents challenges when used on large structures in places (as in conflict zones) where controlling welding parameters is difficult. Two mandatory features of said welds are the retention of greater strength (comparable to the welded component alloys) and the prevention of cracks. At the University of Puerto Rico, we developed a new aluminum-based filler reinforced with a stable diboride nanodispersoid that provides the weld with higher service temperature and strength. This novel material bears enhanced fluidity, which helps reduce leakage rates and improves productivity and weld quality. In addition, when 5% magnesium is added to the filler melt, one can obtain better welded joins for AA 6xxx base alloys, making feasible TIG welding of complex extruded shapes. The addition of niobium diboride nanoparticles upon stir casting processing of the filler alloy can raise its hardness to 11% compared to the unreinforced filler. NbB2 nanoparticles also serve as heterogeneous nucleation sites promoting small grain microstructures with higher yield strength. This leads to a filler that can compete with commercial ones that require post-welding treatment to achieve proper microstructure and strength.