Formation of a nanocrystalline (Ti,V)C reaction layer during active wetting of graphite with Ag-Cu filler alloy

Active brazing of carbon-based materials requires carbide-forming elements to promote interfacial reactions and enable wetting. This study investigates the combined effect of titanium and vanadium on the wetting behavior and interfacial microstructure between graphite and an Ag-Cu eutectic filler alloy at 1000 °C for 20 min. Graphite substrates coated with a Ti-V powder mixture exhibited effective wetting (apparent angle 23°), accompanied by infiltration of the molten alloy into substrate porosity. Microstructural analysis revealed the formation of a continuous nanocrystalline carbide layer identified as a (Ti,V)C solid solution. The results indicate that titanium governs carbide formation and wetting initiation, while vanadium is incorporated into the TiC lattice, modifying the reaction pathway. Notably, the Ti-V coating reduces the formation of brittle Ti-Cu intermetallic compounds compared to systems containing only Ti, promoting a more homogeneous interface. These findings demonstrate that wetting in this system is driven by interfacial reactions and highlight the potential of Ti-V active coatings for the brazing of carbon-based materials.