Laser Additive Manufacturing of Oxide Dispersion-Strengthened Copper–Chromium–Niobium Alloys

Abstract

Copper is a key material for cooling of thermally stressed components in modern aerospace propulsion systems, due to its high thermal conductivity. The use of copper materials for such applications requires both high material strength and high stability at high temperatures, which can be achieved by the concept of oxide dispersion strengthening. In the present work, we demonstrate the oxide reinforcement of two highly conductive precipitation-strengthened Cu-Cr-Nb alloys using laser additive manufacturing. Gas-atomized Cu-3.3Cr-0.5Nb and Cu-3.3Cr-1.5Nb (wt.%) powder materials are decorated with Y2O3 nanoparticles by mechanical alloying in a planetary mill and followed by consolidation by the laser additive manufacturing process of laser powder bed fusion (L-PBF). While dense specimens (>99.5%) of reinforced and nonreinforced alloys can be manufactured, oxide dispersion-strengthened alloys additionally exhibit homogeneously distributed oxide nanoparticles enriched in yttrium and chromium next to Cr2Nb precipitates present in all alloys examined. Higher niobium contents result in moderate increase of the Vickers hardness of approx. 10 HV0.3, while the homogeneously dispersed nanometer-sized oxide particles lead to a pronounced increase of approx. 30 HV0.3 in material strength compared to their nonreinforced counterparts.