Additive nanomanufacturing and dry printing tunable bimetallic nanocomposite and compositionally graded structures

Abstract Printed and additively nanomanufactured multifunctional devices and systems require the ability to print tunable nanocomposites and compositionally graded materials for applications ranging from biomedical to energy devices. Yet printing these with the current ink-based approach often requires complex ink chemistry and formulations that lack compositional tunability in flight. Here, we demonstrate inkless printing of Ag-Cu nanocomposites using a dry additive nanomanufacturing process in which nanoparticles are generated in situ by pulsed-laser ablation of solid Ag and Cu targets and are deposited through a nozzle under argon while a second laser sinters the deposit during printing. Composition is programmed via periodic, automated target switching and ablation-throughput control, enabling discrete Ag: Cu ratios from 100:0 to 0:100 and continuous spatial gradients. Micro- and nanoscale electron microscopy show that as-deposited films consist of porous nanoparticle agglomerate networks, whereas the sintered samples are densified, reducing the surface void-opening area fraction. The porosity and densification levels are also controlled via a tunable laser sintering process during deposition. Energy-dispersive X-ray spectroscopy mapping confirms submicron-scale co-deposition and near-linear agreement between programmed and measured compositions, with a maximum deviation of 7 wt% at mid-range ratios, within the measurement uncertainty. Scanning transmission electron microscopy reveals crystalline primary nanoparticles with early-stage necking. X-ray diffraction shows composition-dependent fcc Ag and fcc Cu diffraction features, systematic peak broadening and shifts, and lattice-parameter trends consistent with nonequilibrium chemical mixing and microstrain. XRD also supports the results that the deposited composition series tracks the programmed setpoints, with a maximum deviation of 2.5% at 50:50. Finally, discrete and graded Ag-Cu patterns are demonstrated on polyimide, confirming composition programmability on flexible substrates.