Abstract:SiC_w/6061Al composite was fabricated with squeeze casting method, hot extruded and superplastically tensile tested. At the temperature of 570℃and the strain rate of 2.0×10^-3 s^-1, an elongation of 280% was obtained. The change of grain shape, dislocation density and distribution was observed by TEM. The results show that during the superplastic deformation grain shape on the whole is unchanged, but the dislocation density and distribution vary quite a lot with the tensile action. Under the optimal straining conditions, dislocation mainly distributes along the grain boundary, which has an important effect on cooperative strain especially. When the strain magnitude is big enough, there appears stacking faults and twin crystals, which also has some effect on the cooperative strain.

Key words: composite; superplasticity; grain dislocation; stacking fault; twin crystal
CLC number: TB333