Microstructure and mechanical properties of Inconel 738LC joint by wide gap brazing using Amdry 718

In this research, Inconel 738LC as the base metal was joined by wide gap brazing (WGB) using the mixture of Amdry718 as high temperature particle (HTP) and BNi-2 as low temperature particle (LTP). By using Amdry 718, the brazing temperature can be increased and porosity reduced significantly due to higher melting point temperature than base metal. The effect of mixture ratio on the microstructure and the mechanical properties was studied. The amount of the LPT in the mixture was 30, 40, and 50 percent. By decreasing the LTP ratio, the amount of eutectic phase and the blocky boride in the solid diffusion zone (SDZ) decreased markedly. The joint width increased by increasing the amount of LTP. There were two distinct regions in the joint/base interface. Due to the diffusion of B into the base, adjacent to the joint, the grain boundary melted and created a region including both the isothermal solidification zone (ISZ) and SDZ. By getting away from the joint, the content of B reduced by the grain-boundary diffusion. It was observed that aging did not have a significant effect on the amount and distribution of eutectic phases and blocky borides, however, the morphology of these phases changed slightly. Moreover, aging had a small effect on hardness making the hardness of different phases more uniform.