Multi-Scale Mechanical Characterization of Additively Manufactured GRCop-42 and GRCop-84 Alloys

Additive manufacturing (AM) of copper alloys is gaining traction in high-performance applications such as rocket engine combustion chambers and heat exchangers. This study investigates the microstructural and mechanical behavior of two Cu-Cr-Nb alloys, GRCop-42 and GRCop-84, fabricated via laser powder bed fusion (L-PBF) and laser powder-directed energy deposition (LP-DED). A multiscale approach was used to relate micro/nanoscale features to macro-scale mechanical properties, with particular focus on the relationship between hardness and tensile strength. Indentation-derived properties, including plasticity index and elastic recovery, were also assessed. The results show that L-PBF-processed GRCop-42 specimens exhibit higher strength but lower elastic modulus compared to LP-DED counterparts. The strength-hardness correlation varied significantly depending on the processing method. Notably, for L-PBF samples with weak to moderate texture, hardness correlated well with tensile strength, with deviations between 2% and 16%. However, in LP-DED specimens exhibiting strong crystallographic texture, this correlation weakened due to anisotropic mechanical response. These findings highlight the influence of processing-induced microstructures on mechanical performance and provide practical insights into using hardness as a predictive metric for tensile properties in AM copper alloys.