High-precision Cu alloy microlattices with superior energy absorption capacity enabled by nanoprecipitation engineering

Printing of thin-wall copper alloy components with high mechanical performance using selective laser melting remains challenging. Here, the introduction of the soft Cr nanoprecipitations via increasing the Cr to Nb atomic ratio based on commercial CuCrNb alloys can suppress the excessive formation of Cr₂Nb Laves phase and enhance the deformability of CuCrNb microlattices. Small printing layer thickness contributed to the high-density and small-size nanoprecipitations. Dual nanoprecipitations strategy enables us to successfully fabricate high-precision CuCrNb microlattices with the feature size down to 100 µm and exceptional printability, high mechanical strength, and homogeneous deformability until densification strain. By tailoring the precipitation behavior of Cr phase at post-printing stage, CuCrNb microlattices can further enhance the mechanical performance. Our peak-aged Gyroid CuCrNb microlattice displays an ultrahigh specific energy absorption of 23 J/g without fracture at strain above 60 %, even surpassing that of some titanium and aluminum alloys lattice structures with low material densities. © 2023 Acta Materialia Inc. Published by Elsevier Ltd.