REACTIVE-INFILTRATION PROCESSING OF SIC-METAL AND SIC-INTERMETALLIC COMPOSITES

Liquid-phase reactive infiltration is a rapid and net-shape method of synthesizing silicon carbide composites. We use reactive infiltration of carbon with Si-Al and Si-Cu melts to prepare composites consisting of interpenetrating networks of beta-SiC and a secondary phase assembl age containing ductile metal (Al-Si) or a metal silicide (Si-Cu). The mechanisms of phase formation have been characterized It is shown that a rapid initial reaction upon infiltration forms a largely stationary SiC network, within which the secondary phase constitution evolves du e to solute rejection and liquid phase diffusion processes. Both homog eneous composites and those with controlled composition gradients have been synthesized.