EXAFS investigation of the local atomic structure of Fe-Ge nanocrystalline disordered alloys

Abstract

This paper reports on the results of EXAFS investigations (Fe K and Ge K absorption edges) of binary supersaturated nanocrystalline solid solutions Fe100−x Ge x (x = 15–40 at % Ge) prepared by mechanical alloying. The nanocrystalline disordered structure of the single-phase alloys is characterized using X-ray diffraction, Mossbauer spectroscopy, and magnetic measurements. The EXAFS spectra are analyzed by solving the inverse binary problem with the use of combined data on the Fe K and Ge K absorption edges. The parameters of the partial pair correlation functions obtained indicate that the crystal lattice is characterized by strong local static distortions and short-range chemical order increasing with an increase in the germanium content. Moreover, the formation of a hexagonal-type macrostructure in the body-centered cubic (bcc) lattice occurs through a “local” stage.