| Abstract Scope |
This study presents an in-situ method for synthesizing nanoscale strengthening particles during Directed Energy Deposition (DED) by injecting reactive gases (e.g., N₂, O₂) into the melt pool. Gas-metal reactions generate nanoparticles such as Cr₂N in SS316 and Al₂O₃ in AlSi10Mg alloys during solidification, eliminating the need for mechanical alloying. Rapid cooling (10³–10⁵ K/s) and Marangoni-driven convection promote uniform nanoparticle dispersion (50–500 nm) and refined grain structures (<5 μm). Multiscale characterization (TEM, EBSD) reveals enhanced mechanical properties, including over 20% improvement in hardness. A semi-empirical model linking gas chemistry, processing parameters, and nanoparticle yield is developed and validated with computational simulations. This integrated approach offers an energy-efficient pathway for fabricating dispersion-strengthened alloys tailored for extreme environments, advancing additive manufacturing capabilities in aerospace, energy, and nuclear sectors. |