Laser powder bed fusion of nano-titania modified 2219 aluminium alloy with superior mechanical properties at both room and elevated temperatures : The significant impact of solute

There is a strong demand for facile and cost-effective approaches for additive manufacturing (AM) of aluminium (Al) alloy parts with high mechanical properties at both room and elevated temperatures via laser powder bed fusion (L-PBF). Such alloys must be devoid of cracks and large pores while exhibiting excellent mechanical performance. In this study, we demonstrated that the addition of 1 wt% titania (TiO₂) nanoparticles to a 2219 Al alloy could substantially prevent hot-crack formation during L-PBF by significantly refining grains, which resulted in the formation of a nearly fully dense alloy with a high relative density (99.97%). This pronounced grain refinement was due to the solute effect of the Ti element with a high grain growth restriction factor (Q value) instead of the in-situ formation of lattice-matched L1₂-ordered Al₃Ti particles. The processed alloy displayed an excellent combination of high ultimate tensile strength and elongation at both room and elevated temperatures, with these properties being comparable to those of its wrought counterpart and greater than those of 2219 Al alloys fabricated via other AM techniques. This low-cost pathway can also be applied to the AM of other Al alloys, which demonstrates its commercial significance.