Solidification sequence of Ni-Si-Cr ~3wt% B brazing alloys

Various Ni-Si-Cr-B brazing alloys with a similar boron content (3 wt%) are investigated. Alloy compositions cover a section of the quaternary phase diagram that connects BNi-3 to BNi-9 ternary alloys for industrial use. Samples were melted and solidified at low cooling rate (1 K/min) under secondary vacuum to minimize oxidation and the metastable phase formation. Transformation temperatures, microstructures, and chemical analyses are reported. Experimental conditions were found to play a significant role on the accuracy of obtained data. Thermodynamic data were collected upon heating. Before analyzing quaternary alloys, the results of investigated ternary alloys were compared with the literature and discussed.The authors thank Etablissements Chpolansky, Marcoussis, France, which kindly provided the certified commercial brazing alloys. Dr. J. Zollinger calculated the equilibrium ternary alloy phase diagrams with Thermo-Calc® and the TTNi7 database. M. Bertrand, master student, also contributed to this study. Finally Dr. L. Peltier and P. Charbonnier realized a secondary vacuum furnace which allowed melting of these alloys. The authors thank NSERC and CRIAQ for their indirect financial support on related projects