(351f) Versatile Additive Manufacturing of Microscale Metals and Alloys Via Hydrogel Infusion

Additive manufacturing (AM) of metal components has emerged as a uniquely powerful tool for rapid prototyping and creating parts with complex geometries and applications from aerospace to biomedical industries. We explore AM enabled by digital light processing (DLP), typically used to produce polymers and ceramics, for the fabrication of metals and metal alloys. This addresses a long-standing gap in conventional metal AM processes, which struggle to fabricate metals at the mesoscale, with feature sizes in the 10-100 µm range.

We developed a general method for the fabrication of a wide variety of metals and alloys with complex shapes, mesoscale resolution, and overall cm-scale dimensions via DLP AM and subsequent post-processing and thermal treatment. This streamlined technique makes use of a single resin composition and a single set of processing conditions during the DLP process, followed by infusion of appropriate metal precursors into a hydrogel structure. Heat treatment in oxidizing followed by reducing atmospheres converts the polymer/precursor matrix into the target metal. Unlike previous vat photopolymerization strategies which have target materials or precursors incorporated into the resin during the printing process, this method does not require re-optimization of resins and resin curing parameters when the target material is changed; relevant process control parameters are shifted to the hydrogel infusion and heat treatment steps.

We report photoresin design and post-processing strategies to show how to use this technique to easily fabricate a range of AM metal and alloy structures. As a proof of concept, we fabricated octet lattice architectures with beam diameters on the order of 50 µm from several materials including copper, nickel, silver, cobalt, cupronickel alloys, tungsten, and multicomponent high entropy alloys. Furthermore, we demonstrate fabrication of multi-material metal structures via this method. Throughout, we investigate the relationship between processing and microstructure of these additively manufactured materials and highlight the wide-ranging versatility of achievable materials and microstructures.