A process for producing an internal cavity in a CMC article and mandrels used therewith. The process entails incorporating a mandrel made of a fusible material that is melted and drained during a thermal treatment of a CMC preform to form the CMC article. The mandrel material is preferably non-wetting and non-reactive with any constituents of the CMC preform during the thermal treatment. The mandrel is preferably tin or an alloy of tin.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 This invention was made with government support under Contract No. DE-FC26-05NT42643 awarded by Department of Energy. The Government has certain rights in this invention.