Deformation Induced Microstructure of L1₂ Ordered γ′-Ni₃(Al, Ti) Single Crystals Containing Fine Dispersion of Disordered γ Precipitates

Abstract

Morphology of dislocations in deformed γ′-Ni₃(Al, Ti) single crystals containing fine dispersion of disordered γ particles has been investigated by means of weak beam dark field transmission electron microscopy. Superlattice dislocations dissociate into fourfold Shockley partial dislocations in a uniform supersaturated solid solution of the γ′ phase. Dislocations are attracted into the disordered γ phase and dissociate further in the particles. At any stage of aging, dislocations cut through the particles and the Orowan bypassing process dose not occur even in the overaged stage of this alloy system. The work necessary to pull the dislocation away from the disordered particles into the ordered matrix should mainly contribute to increase the strength of the γ′ phase containing fine dispersion of the disordered γ phase.