A process for producing an internal cavity in a CMC article and mandrels used therewith. The process entails incorporating a mandrel made of a material that is substantially absorbed during thermal treatment of a preform to form the CMC article. The mandrel material is preferably reactive with one or more constituents of the CMC preform during the thermal treatment. The material is preferably silicon or a silicon alloy.
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.