DISLOCATION PINNING IN HIGH TEMPERATURE DEFORMED Ni3(Al,Ti) SINGLE CRYSTALS CONTAINING DISORDERED γ PRECIPITATES

A transmission electron microscopy (TEM) investigation has been performed on the dislocation pinning in L12-ordered Ni3(Al,Ti) containing disordered γ precipitates. The morphology of deformation induced dislocations in the γ′ base alloys containing fine dispersion of disordered γ was investigated by means of weak-beam electron microscopy. The superdislocations are strongly attracted to the disordered particles and dissociate on the (111) plane in the γ particles, while they dissociate on the (010) plane in the γ′ matrix. The disordered γ precipitates play an important role as a pinning point during the cross-slip of superdislocations from (111) to (010) planes in the γ′ matrix and restrain the cross-slip of superdislocations. The interaction of superdislocations with disordered particles causes the formation of superkinks, jogs and closed loops.