Enhanced Braze Wetting on Electroplated L-PBF Additive Manufactured GRCop-84 and GRCop-42, Stainless Steel, and Refractory Alloys

Laser powder bed fusion (L-PBF) of Glenn Research Copper 84 (GRCop-84) and Glenn Research Copper 42 (GRCop-42), Cr2Nb precipitation hardened alloys, produces a fully dense, high conductivity alloy. Cr2Nb precipitates impede free flow of liquid braze material across the surface of these alloys, similar to the observations of CuCrZr alloy brazing. This effect prevented effective vacuum brazing of additive manufactured GRCop waveguides into stainless steel waveguide flanges, where free flow into the waveguide-in-socket joint was required. The electroplating of copper and nickel alloys onto GRCop alloys showed enhanced wetting and free flow by covering surface precipitates. Braze wetting onto plated 304 and 316 stainless steels and active braze wetting on Inconel 625, tungsten, and TZM alloys used in flanges and limiters were evaluated.