Measuring interdiffusion coefficient from XRD spectra of thermally annealed superlattices: A combined modeling and experimental study in Fe-Cr nanometric multilayers

Abstract

In this paper, we employ atomic kinetic Monte Carlo (AKMC) simulations to get insight into the kinetics of Fe-Cr interdiffusion in nanometric multilayer materials, and the relevant information that can be extracted from the evolution of the experimental X-ray diffraction (XRD) spectrum. For this purpose, we develop an elastic model to obtain the interplanar spacing for a given composition profile derived from AKMC simulation, and then we simulate the corresponding XRD spectrum and compare it with the experimental one. We find a very good agreement between the two, which validates our modeling procedure. Then we put some effort into trying to relate specific features of the XRD spectra with phenomena occurring at the atomic scale, mostly the decay of satellite peak intensities over time. The interdiffusion coefficients extracted from the XRD spectra are underestimated in the Fe-rich phase and overestimated in the Cr-rich phase, but more or less within one order of magnitude of the values obtained from standard measurements. Extracting more quantitative kinetic information directly from the experimental XRD spectra is rather difficult without resorting to a modeling study.