Near-neighbor mixing and bond dilation in mechanically alloyed Cu-Fe

Abstract

Extended x-ray-absorption fine-structure ͑EXAFS͒ measurements were used to obtain element-specific, structural, and chemical information of the local environments around Cu and Fe atoms in high-energy ballmilled Cu x Fe 1Ϫx samples ͑xϭ0.50 and 0.70͒. Analysis of the EXAFS data shows both Fe and Cu atoms reside in face-centered-cubic sites where the first coordination sphere consists of a mixture of Fe and Cu atoms in a ratio which reflects the as-prepared stoichiometry. The measured bond distances indicate a dilation in the bonds between unlike neighbors which accounts for the lattice expansion measured by x-ray diffraction. These results indicate that metastable alloys having a positive heat of mixing can be prepared via the high-energy ballmilling process. ͓S0163-1829͑96͒10033-3͔

Local atomic structure in iron copper binary alloys: An extended X-ray absorption fine structure study

“…1(b) have been corrected for electron phase shifts using the first shell-path from FEFF and therefore, the FT peaks should correspond directly with the true bond distances of the near neighbours. Results of the first coordination shell fitting parameters obtained are: an Fe-Fe coordination number of 7.9 ± 0.3 at a distance 0.248 ± 0.002 nm, r 2 = (41 ± 5) · 10 À4 Å 2 and DE 0 = 7.16 eV; whereas the corresponding values for the second shell are N = 6.2 ± 0.2, R = 0.285 ± 0.002 nm, r 2 = (48 ± 5) · 10 À4 Å 2 and DE 0 = 7.16 eV; in agreement with the parameters known in the literature [24]. The estimated errors are the standard ones for EXAFS.…”

Neutron induced damage in reactor pressure vessel steel: An X-ray absorption fine structure study

“…The estimated errors are the standard ones for EX-AFS. These values are in agreement with the parameters known in the literature [23] for a bcc unit-cell of an Fe lattice. Describing the situation for the annealed one (IA specimen), the best fit is obtained with similar values for first two shells.…”

“…In our analysis, Kedges final-state potentials for the central atoms (i.e., Cu, Ni or Mn) were calculated using atomic clusters derived from the known atomic coordinates of body-centered-cubic (bcc) phase Fe structures as referred in Refs. [23,24].…”

Electrochemical and physical characterization of Ni-Cu-Fe alloy for chlor-alkali hydrogen cathodes

“…For 3d-metals with cubic crystal symmetry such as Ni, this pre-edge structure is due to electronic transitions from the 1s level to a series of p-like empty energy states in the metal d-band, just above the Fermi level [12,13,20]. The hump at about 15-20 eV above the edge can be associated to electron excitations from the 1s to higher energy p-states [13,20], but they may also correspond to the multiscattering of the incident beam by nearly located atoms in the metal crystal, as specifically interpreted for Fe [14,21].…”