Local atomic configuration in mechanically synthesized Co-Fe-Ni alloys

Ternary Co-Fe-Ni alloys were prepared from the elemental powders by the mechanical alloying method. Structural properties and hyperfine interactions parameters were determined using X-ray diffraction and Mössbauer spectroscopy. X-ray diffraction proved that during milling Co-Fe-based solid solutions with b.c.c. lattice were formed in the case of Co40Fe40Ni20 and Co50Fe40Ni10 alloys, while for Co52Fe26Ni22 and Co65Fe23Ni12 compositions Co-Ni-based solid solutions with f.c.c. lattice were obtained. Mössbauer spectroscopy revealed similar values of the average hyperfine magnetic fields for all the alloys. These values corresponded to the different surroundings of 57Fe isotopes by Co, Fe and Ni atoms, depending on the chemical composition of the alloy. The possible atomic configurations around 57Fe isotopes were discussed on the basis of the local environment model under the assumption that only the first nearest neighbours contribute to the hyperfine magnetic field at 57Fe site.