EXAFS, X-ray diffraction and Mِssbauer studies of an amorphous Fe60Ti40 alloy produced by mechanical alloying

The local atomic structure of an amorphous Fe60Ti40 alloy produced by mechanical alloying was investigated using the extended X-ray absorption fine structure (EXAFS), X-ray diffraction (XRD) and Mössbauer spectroscopy techniques. From the EXAFS spectra at the Fe and Ti K-edges, the radial structure functions were obtained and the EXAFS χ(k) near neighbor oscillations were isolated. By fitting these functions with a least-squares method the coordination numbers and interatomic distances were determined. Independently, the total structure factor S(K) for this alloy was deduced from the XRD measurements, and, by Fourier transforming, the total radial distribution function RDF(r) was obtained. The theoretical total structure factor S∗(K) predicted by the additive hard-sphere model for a mixture of Fe and Ti atoms with the same composition was calculated. There was a strong resemblance between the amorphous structure investigated and that predicted by this model, specially for the Fe–Fe and Fe–Ti pairs. A comparison between the local atomic structure found in the amorphous Fe60Ti40 alloy and in the FeTi compound was made.