This NASA sponsored STTR project will investigate methods for close-out of large, liquid rocket engine nozzle, coolant channels utilizing robotic laser and pulsed-arc additive manufacturing methods. Copper to Nickel alloy interface strength will be quantified and metallurgical characterization completed. A thermal model based on Rosenthal?s analytical expression for a moving heat source, which has been incorporated into a numerical model with provision for adding mass, will be used to predict thermal profiles for AM of the close out. The model will be verified and validated for different material combinations investigated in this study. Keystone will also investigate high temperature stability of the interface Cu-to-Ni layer through thermal treatments. After application of Ni layers and the thermal treatments at varying temperature and times, X-ray diffraction (XRD) will be used to document phases present and analyzed for formation of potential detrimental effects.