INGOT PROCESSING AS AN ALTERNATIVE TO POWDER PROCESSING FOR ACHIEVINGSUPERPLASTICITY IN CERAMICS

The mechanical behavior of an iron carbide base material processed by an ingot route was compared with that of the same composition material processed by a powder route. Thermo-mechanical processing routes have been developed to refine the coarse as-cast ingot microstructure. Str uctural refinement is a result of creation of strain-free regions by c arbon dissolution from high strain energy subgrain boundaries and slip bands. The ingot-processed iron carbide material exhibits superplasti c behavior and deforms by the same grain boundary sliding mechanism as for the powder-processed material. It is proposed that thermo-mechani cal processing of ingot-cast eutectic-composition ceramics to achieve a superplastic structure is feasible.