Dislocation Substructure Analysis in γ′-Precipitated Ni-Based Alloy by X-Ray Diffraction Combined with Positron Annihilation

The systematic changes in the dislocation density and characteristics of γ′-precipitated Ni-based model alloys that develop under cold rolling are studied as simulated deformations, to examine the fundamental dislocation behavior in terms of the dislocation substructure formation. In particular, the dislocation density is quantified through X-ray line profile analysis (XLPA), which is effective for quantifying the dislocation density and characteristics, as well as positron annihilation lifetime (PAL) measurements, which are sensitive to vacancy-type lattice defects. Similar tendencies are obtained for the strain dependency of the dislocation density analyzed using XLPA and PAL. Hence, the influence of the γ/γ′ coherent interface and γ′ precipitation on the dislocation substructure and vacancies is shown by comparing with a Ni-Cr solid solution. These results help to understand the interaction of solute atoms, vacancies, and dislocation with regard to substructure formation in Ni-based alloys.