Microstructure evolution and fracture behavior of 2060 Al[sbnd]Li alloy by laser welding with TiC nanoparticle-reinforced filling wire

Abstract

Laser welding could provide thermal concentration and penetration to alloys, making microstructural diversity that determines mechanical properties. During laser welding process of aluminum alloys, one of the most important characteristics is the inhomogeneity of microstructure. The study demonstrated microstructure transformation of 2060 aluminum-lithium (AlLi) alloy in laser welding technique using TiC nanoparticle-reinforced filling wire to tailor mechanical properties. Furthermore, the study unveils the microstructural configuration achieved during laser welding of the 2060 AlLi alloy, along with its fine-scale mechanical behavior. The results show that the microstructure of weld seam (WS) with TiC nanoparticle-reinforced ER2319 filling wire was dominated by fine equiaxed crystal, which indicated that the addition of nanoparticles promoted the transformation from columnar crystal to equiaxed crystal. Compared with conventional ER2319 filler wire, the grain size with adding TiC nanoparticles reduced by 47 %, and the strong texture feature of Al-matrix on (001) base plane tended to disappear. Furthermore, the tensile strength and elongation of WS were increased by 8.6 % and 195.5 %, respectively. The direction of crack propagation is deflected under filler ER2319CT wire, gradually tends to be perpendicular to the load direction. This is attributed to the fact that the dispersed TiC particles in WS hinder the movement and migration of dislocations resulting in an increase of strength.