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 matri x materials and reinforcing fibers which are rarely at thermodynamic e quilibrium. The use of coatings to protect the fibers from deteriorati ng reactions at the interface adds processing and manufacturing costs. If structural composites are going to be synthesized competitively, w e must find in-situ processes that can produce thermodynamically stabl e interfaces between the matrix and the reinforcement. One such proces s 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 desir able microstructure for structural composites via the solid-state disp lacement reaction are formulated. They are applied to a ternary silico n-metal-carbon system for possible synthesizing a metal silicide-silic on carbide composite.