Abstract: The effect of prior warm-deformation on superplasticity was studied by means of tensile tests for SiCp / MR64 composites. 10%SiCp / MR64 showed tensile elongations in excess of 210% at an initial strain rate of 8.33 10-3s-1at 500℃ , and after prior-worked to 35% at 300℃ the maximum elongation of 305% was obtained for superplastic test. Metallographic and cavitation behavior observations showed that continuous recrystallization took place in materials prior-worked during superplastic deformation, which fined the grain sizes, and the prior-working process also reduced the level of cavitation. It is concluded that the decreased number of cavites is the main reason for the improved superplastic ductility.

Key words: superplasticity, SiC particulate, composites, cavity