Molten metal jetting of pure silver with micro resolution and tailored microstructure

Molten Metal Jetting (MMJ) is emerging as a promising technology in additive manufacturing, enabling precise and high-resolution printing of intricate 3D structures. However, its current application has been limited to low-melting materials and millimetre-scale droplets, underscoring a significant gap in understanding high-temperature microdroplet behaviour during deposition. Here, we developed a comprehensive computational and experimental framework to deepen understanding of the MMJ process for pure silver, focusing on droplet dynamics, solidification kinetics, and interfacial bonding mechanisms. This enabled us to print fully consolidated pure silver structures without the need for post-manufacturing heat treatments, thus overcoming challenges previously reported for high-melting-point materials by precisely controlling the droplet and substrate temperatures. Our findings showed that thermal conditions strongly influence the formation of various microstructures. Cooling rates of 16–23 °C/μs promoted the development of fine equiaxed grains at the interface, followed by directional columnar grains, with annealing twin grain boundaries forming under these conditions. In contrast, slower cooling, at 3.5 °C/μs, due to increased substrate temperatures, resulted in larger grains and the formation of single-crystal structures within the droplets. These findings open new possibilities for tailored microstructure control through MMJ. Eventually, this progress could enable the fabrication of high-resolution electronics in silver, driven by the precise printing capabilities of the MMJ process.