Microstructure and mechanical properties of cold spray additive manufactured Cu-Cr-Nb and Fe-Ni-Cr alloys

The main objective of this work was to investigate the microstructure and mechanical properties of Cu-Cr-Nb (GRCop-42) and Fe-Ni-Cr (HR-1) alloy deposits produced using a high-pressure cold spray process. GRCop-42 powder blended with varying content of HR-1 powder (0, 15, 25, 50, 75, 85, and 100 wt%) was cold spray deposited, and the microstructure and mechanical properties of the deposits were evaluated. The deposits were characterized using optical microscopy, X-ray diffraction, and scanning electron microscopy. The use of He process gas resulted in relatively lower porosity and better mechanical properties compared to the deposits produced with N2 process gas. In the as-deposited condition, all the cold spray deposits exhibited brittle behavior with no appreciable ductility. Post-deposition heat treatment significantly improved ductility and tensile strength for both GRCop-42 and HR-1 deposits. However, post-deposition heat treatment resulted in coarsening of Cr2Nb precipitates in GRCop-42, the formation of eta phase in HR-1, and the formation of sigma phase at the interface in GRCop-42 and HR-1 composite deposits.