Multiscale Microstructural and Mechanical Characterization of Cu–Ni Binary Alloys Reduced During Hydrogel Infusion‐Based Additive Manufacturing (HIAM)

Hydrogel infusion‐based additive manufacturing (HIAM) is a chemically versatile solid‐state processing pathway that allows 3D structuring of ceramics and alloys with micro‐scale precision. Using thermal treatments of 3D‐printed metal ion‐infused gels, this process generates intricate microstructures throughout their complex phase evolution. Through investigation of the HIAM‐produced Cu x Ni 1-x alloy system, substantial grain growth after reduction is shown to drive the formation of numerous annealing twins and entrap unreduced oxide nano‐inclusions, resulting in hierarchical composite microstructures. These features appear to elevate the average nanoindentation hardnesses by up to four times that of bulk annealed Cu x Ni 1-x . Uniaxial compression of micropillars milled from individual grains reveals composition dependence on the scaling of the "smaller is stronger" size effect. This compositional dependence of deformation mechanisms arises from changes in reduction kinetics which influence the density of inclusions and voids developed by the HIAM process. This work highlights the rich microstructural landscape accessible to HIAM‐produced alloys and provides a useful pathway for the characterization and tuning of superior mechanical performance in additively manufactured alloys. ; J.R.G. gratefully acknowledges the financial support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences (DE-SC0016945). T.T.T. acknowledges support by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. The authors acknowledge assistance from Dr. Mingjie Xu and the use of facilities and instrumentation at the UC Irvine Materials Research Institute (IMRI), which is supported in part by the National Science Foundation through the UC Irvine Materials Research Science and Engineering Center (DMR-2011967). ; © 2025 Wiley-VCH GmbH ; Filename Description smll70067-sup-0001-SupMat.docx 2.5 MB SupportingInformation smll70067-sup-0002-MovieS1.avi 32.1 MB Supplemental Movie1 ...