Influence of Ni-Addition on Microstructures and Properties of Seam Brazed with AgCu28 Solder

Herein, we experimentally addressed the brazing in H₂ atmosphere of microwave electric vacuum device components, made of TU1, 4 J33 and Ni-plated 4 J33 alloys, with AgCu28 and AgCu28 Ni0.75 solders.The influence of the addition of Ni in AgCu28 solder on the microstructures, phases and mechanical behavior of the welded seam was investigated with scanning electron microscope, energy dispersive spectroscopy and metallographic microscope.The preliminary results show that the Ni addition had a major impact.To be specific, Ag-Cu eutectic alloy formed at the well-brazed TU1 seam with no grain boundary penetration;AgCu28 Ni0.75 solder was found to seriously diffuse into the grain boundaries of the base metal.In addition, the Ni, added into AgCu28 solder and/or plated on the base metal surfaces, accounted for the significant surface segregation.