Line profile analysis of dislocation densities of the δ-phase 239Pu-2.0 at%Ga alloy using neutron diffraction

Abstract

Time-of-flight neutron diffraction measurements were conducted at ambient conditions to study microstructures of the δ-phase 239Pu-2at% Ga alloy. Based on the line profile analysis of diffraction data we derived dislocation densities using a correction routine to account for the anisotropic strain broadening. Our results show that the average dislocation density in the as-received sample, previously treated at cryogenic temperatures, is five times higher than the dislocation density measured after annealing the sample, indicating that the neutron instrumentation used in this work has sufficient resolution to detect the dislocation density changes in different sample processing. These results are also in reasonably good agreement with the dislocation densities previously reported based on TEM observations and x-ray diffraction data, suggesting that the simple correction routines applied in this work have a fairly good fidelity for deriving important microstructural information such as dislocation density for elastically highly anisotropic δ-phase 239Pu-Ga alloys.