Polytypic transformation and gliding behaviour in polycrystalline α-SiC deformed by compression at high temperatures

Abstract

Hot-consolidated Al-doped α-Sic have been subjected to creep in compression at 1950°C up to 55 MPa in vacuum. Slip bands of dissociated dislocations in the basal plane are the most frequent observation in these deformed samples. If SiC crystals contain some growth defects, the present study demonstrates that other mechanisms as partial dislocation sources can be activated. This can induce the formation of new polytypes such as the 12R polytype. The 4H → 3H polytypic transformation has also been observed. Moreover a certain amount of pyramidal or prismatic glide has been found when the basal slip system cannot operate.