使用兩種填料真空硬銲Incoloy 800之研究

Abstract

In this research, both copper foil and Ni-based V2177 foil are applied in brazing IN-800 substrate. Analyses of the microstructural evolution of the joint by controlling brazing temperature, time and the thickness of foil were performed. Selected specimens were applied in shear test in order to evaluate the effect of microstructure on the brazed joint. First, IN-800/Cu/IN-800 brazed joints show no precipitate, and their shear strengths do not change with the brazing temperature and thickness of the filler foil. The crack is originated from Cu-rich matrix based on SEM microstructure analysis of the fractured surface. IN-800/VZ2177/IN-800 brazed joints include two types of precipitates, B2Cr5P and Cr4Ni3P4, in the Ni-based matrix, and both are coarsened with increasing brazing temperature and/or time. However, B2Cr5P phase is coarsened more prominent than Cr4Ni3P4 at higher temperature due to enhanced diffusion rate of boron at higher temperature. Coarsening of B2Cr5P phase is also enhanced by increasing the thickness of filler foil. Based on the result of SEM microstructural examination and XRD analyses of the fractured surfaces, the crack are originated from B2Cr5P phases, and the shear strength is decreased with the coarsened B2Cr5P phase. Optimized conditions are brazed between 1050℃ and 1080℃ for 10 ~ 20 min and using the foil with 40 μm in thickness.