Modeling and simulation of the TiC reaction layer growth during active brazing of diamond using DICTRA

The growth kinetics of the TiC reaction layer during active brazing of diamond with Cu-Sn-Ti and Ag-Cu-Ti based filler alloy has been investigated by kinetic simulations and comparing with available experimental data. First, to obtain a reliable mobility database, the atomic mobilities of C and Ti in fcc (face-centered cubic) TiC are assessed using software DICTRA based on available diffusion data from literatures. Then, to carry out simulations for GB (Grain Boundary) diffusion in TiC, the bulk activation energy multiplier is determined by evaluating the available GB diffusion data. With the obtained mobility data, the TiC growth for Cu-Sn-Ti-Zr filler as a function of brazing temperature and time is simulated using various possible GB diffusion parameters. Afterwards, the determined GB diffusion parameters are validated by simulating the TiC growth for various Cu-Sn-Ti or Ag-Cu-Ti brazing alloys and comparing the simulated results with experimental data. Based on the optimized GB diffusion parameters, the influence of brazing temperature, filler alloy composition, and braze layer thickness on growth kinetics of TiC are simulated and discussed. Finally, the experimentally observed segregation of Cu at the interface between diamond and TiC layer during brazing of diamond using Cu-Sn-Ti or Ag-Cu-Ti filler is analyzed by diffusion simulations.