A powder metallurgy approach to liquid metal dealloying with applications in additive manufacturing

Liquid metal dealloying (LMD) is a useful materials synthesis technique for fabricating dense metal-metal composites with nanoscale to microscale features and highly tunable mechanical properties. However, LMD has generally been restricted to small part geometries with limited thicknesses or employed as an interfacial effect because the reaction is diffusion-limited, gradually slowing inside the bulk of the precursor alloy, and results in a material with a broad gradient of feature sizes due to surface-diffusion-mediated coarsening of the ligaments. Here we propose powder metallurgy as a solution for the scalable synthesis of LMD composites, where the initial materials are a mix of precursor alloy powders and metal solvent powders, creating a material with uniform features throughout the entire bulk. This approach offers a large degree of control over the morphology of the final composite by tuning key parameters, including the phase fraction of precursor to solvent powders, dealloying temperature, and coarsening time. A powder-based approach also opens the door for a new materials synthesis method that combines the advantages of dealloying and additive manufacturing into a one-step process with architectural control over several orders of magnitude, from the unique bicontinuous morphology of LMD materials on the nanoscale to the geometric freedom accessible via additive manufacturing on the macroscale.