Microstructures and Hardness of Mo Heater Chip Brazed with Au–18mass%Ni

Microstructures and hardness of Mo heater chips brazed with Au–18mass%Ni were investigated. The reaction layer of Mo–Ni compounds forms at the brazed interface. Spherical MoNi compounds form initially, and they change columnar ones with increasing brazing time. The reaction layer grows abruptly when the brazing time is more than 5 minutes with the brazing temperature range from 930 C to 970 C. The Vickers hardness of MoNi is evaluated as 682Hv. That is approximately three and four times those of Mo and the Au–18Ni filler, respectively.