Ultrahigh strength aluminum alloy by green laser additive manufacturing

Infrared laser additive manufacturing of high-strength 7××× aluminum (Al) alloys is hindered by low absorptivity, high cracking-susceptibility, and insufficient precipitation strengthening. Herein, we investigate a new approach to process high-performance AA7075 by integrating green laser directed energy deposition (L-DED) with nano-TiC embedded composite AA7075 powder. The green laser achieves better energy-material coupling, enabling high-quality deposition at a lower laser power than conventional infrared lasers. The green laser also stabilizes the melt pool, reduces thermal gradients and elemental evaporation, and promotes more uniform grains with lower dislocation density. Heat treatment yields an ultra-high density of nano-scale η′ precipitates and GP zones (~2.13×1016 m−2) in the green laser deposited Al alloy, achieving a tensile yield strength of ~600 MPa, which is higher than forged AA7075 and almost all L-DED-processed Al alloys hitherto reported. This work presents an integrated material-process strategy for additive manufacturing of highly reflective, hot-crack-susceptible alloys using short-wavelength lasers. Cracking and poor laser absorption curbed additive manufacturing of high-strength aluminium alloys. Using a TiC/AA7075 composite powder and a green wavelength laser, researchers produced crack-free aluminum alloy with a yield strength of nearly 600 MPa.