Magnetic properties of nanocrystalline Fe_xCu_1-x alloys prepared by ball milling

X-ray diffraction, Mössbauer and magnetization measurements were used to study Fe_xCu_1-x alloys prepared by ball-milling. The X-ray data show the formation of a nanocrystalline Fe-Cu solid solution. The samples with x ≥ 0.8 and x ≤ 0.5 exhibit bcc or fcc phase, respectively. Both the bcc and fcc phases are principally ferromagnetic for x ≥ 0.2, but the sample with x = 0.1 remains paramagnetic down to 78 K. The influence of the local environment on the hyperfine parameters and the local magnetic moment are discussed using calculations based on the discrete-variational method in the local density approximation.