In this study, thermodynamic and kinetic simulations with Thermo-Calc and DICTRA software
were utilised to predict the microstructural evolution observed in brazing of high-strength nickel
base single crystal superalloy, CMSX-4, with two commonly used filler metals (FMs), AWS BNi-2
(AMS 4777) and AWS BNi-9. DICTRA diffusion models of the Ni-B binary system were used to
calculate base materials dissolution, the amount of centreline eutectic constituents and time
required for complete isothermal solidification at various joint gaps. Thermo-Calc simulations
using the CALPHAD technique predicted transformation temperatures and equilibrium phases
of the joints based on the chemical compositions of the two FMs. Experimental brazing and characterisations
of joint microstructure at various brazing temperatures, hold times and joint gaps
were used to validate the simulation modelling results. Good correlation with both Thermo-Calc
and DICTRA simulations and empirical data demonstrated the benefits of using this modelling
approach for braze joint development and applications.