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Brazing, Laser, and Electron-Beam Welding of Additively Manufactured GRCop-84 Copper for Phased Array Lower Hybrid Launchers

2020; Institute of Electrical and Electronics Engineers; Volume: 48; Issue: 6 Linguagem: Inglês

10.1109/tps.2019.2963638

1939-9375

Andrew Seltzman, S.J. Wukitch,

Diamond and Carbon-based Materials Research

Recent advances in selective laser melting 3-D printing technology allow additive manufacturing of lower hybrid current drive (LHCD) RF launchers from a new material, Glenn Research Copper 84 (GRCop-84), a Cr 2 Nb (8 at. % Cr, 4 at. % Nb) precipitation hardened alloy, in configurations unachievable by conventional machining. Cr 2 Nb crystals pin grain boundaries within the copper matrix resulting in high tensile strength and resistance to annealing at elevated temperatures. Brazing, laser, and electron-beam welding (EBW) techniques are explored for joining a thin-walled GRCop-84 waveguide with zero porosity and minimal internal surface roughness. GRCop-84 wets well with the silver solder, CuSil, and Cusil-ABA brazes, once the durable surface oxide is mechanically removed. GRCop-84 melt pool size and flow during EBW is reduced compared to oxygen-free copper (OFC). Pulsed laser and e-beam welding maintains the Cr 2 Nb precipitate size; precipitate coarsening occurs in conduction mode e-beam welding.