APPLICATION OF THERMODYNAMICS, PHASE-EQUILIBRIA AND KINETICS TO IN-SITU COMPOSITE SYNTHESIS VIA TERNARY SOLID-STATE DISPLACEMENT-REACTIONS

High-temperature structural composites being developed today use matrix materials and reinforcing fibers which are rarely at thermodynamic equilibrium. The use of coatings to protect the fibers from deteriorating reactions at the interface adds processing and manufacturing costs. If structural composites are going to be synthesized competitively, we must find in-situ processes that can produce thermodynamically stable interfaces between the matrix and the reinforcement. One such process which is being developed to synthesize structural composites is via a ternary solid-state displacement reaction. In the present paper, the thermodynamic and kinetic conditions governing the formation of desirable microstructure for structural composites via the solid-state displacement reaction are formulated. They are applied to a ternary silicon-metal-carbon system for possible synthesizing a metal silicide-silicon carbide composite.