Al–Zn–Mg–Cu alloy with both high strength and high plasticity fabricated with wire arc additive manufacturing

To overcome the strength–ductility trade-off dilemma, the microstructure of Al–Zn–Mg–Cu alloy was controlled by adding TiN nanoparticles and heat treatment successively. Al–Zn–Mg–Cu alloy deposition with both high strength and high elongation was achieved. The tensile strength, elongation, and microhardness were increased by 122.3%, 173.9%, 86.1%, and 82.5%, respectively. The columnar grains were completely transformed into equiaxed grains with the addition of TiN particles and the grain size was reduced by 92.9%. The elongation increase was mainly because of the grain refinement, and the distribution fluctuation of the properties decreased. After T6 heat treatment, the elongation remained high because the grain size changed negligibly. Precipitation strengthening is the main mechanism for the improved tensile strength and hardness.