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Thermodynamic and kinetic simulations of high temperature brazing: microstructure evolution in CMSX-4 joints

2016; Maney Publishing; Volume: 22; Issue: 5 Linguagem: Inglês

10.1080/13621718.2016.1250432

1743-2936

Bryan B. Riggs, Boian Alexandrov, Avraham Benatar, Ray Xu,

Nuclear Materials and Properties

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.