Magnetic and structural study of FCCγ‐Fe precipitates in Cu

Magnetization, X‐ray absorption fine structure, and resistivity measurements on two samples of Cu + 2.0 at% Fe are reported here. The first sample, prepared by annealing at 950 °C for 2 days followed by rapid quenching, consists of a random solid solution of Fe in Cu. The paramagnetic susceptibility follows the Curie–Weiss law 10 K ≤ T ≤ 300 K yielding an effective Fe moment of 1.9 ± 0.1 µ B and a Curie temperature −2.0 ± 2.0 K. The second sample, prepared using the heat treatment above followed by a second annealing at 620 °C for 2 h, consists of face‐centered‐cubic (FCC) γ ‐Fe precipitates in the Cu matrix. The formation of the Fe precipitates reduces the electronic scattering, which is reflected in the resistivity behavior. The FCC atomic short‐range order for the Fe is demonstrated with X‐ray absorption fine structure. The paramagnetic susceptibility follows the Curie–Weiss law 100 K ≤ T ≤ 300 K yielding an effective Fe moment of 1.8 ± 0.2 µ B and a Curie temperature −58 ± 10 K, consistent with an antiferromagnetic (AFM) ordering. The results are discussed in the light of previous neutron investigations of the ordered magnetic structure.