Thermodynamic and experimental modeling of interfacial reactivity in metal matrix composites
Résumé
Thermodynamic calculations based on a new assessment of the C-Si-Ti phase diagram were conducted to simulate the interfacial reactivity in the SCS-6iTi-22Al-23Nb composite. The solid state consolidation as well as extreme operating conditions were thus investigated in terms of available matrix towards rapidly diffusing coating material. Additionally, model interfaces were experimentally set up to study the interfacial reactions and the role of the external C-rich layer of the fiber. A carbon-silicon film was deposited by CVD on an aluminide substrate and also specimens of the matrix material were immersed in mixtures of SiC and C ultrafine powders and exposed to temperatures approximating those of composite fabrication. Interactions between the aluminide and CVD deposits or powder mixtures were investigated and simultaneous formation of carbide and silicides was observed in the interface. Information collected fi om thermodynamic modeling and from model-systems in terms of thickness and composition was found in agreement with the extend and the composition of the interface in the composite material.