Sol–gel preparation and characterization of NiCo and Ni3Fe nanoalloys

► Nanoalloys of NiCo and Ni3Fe were prepared by sol–gel process based on chelating of citric acid under N2 or H2 atmosphere. ► The nanoalloys are with quilibrium ordered phase structure formed without post-annealing treatment. ► The average grain size of the nanoalloys is fine and the grain size distribution is narrow. Sol–gel process is effective in preparation of metallic oxides. Here we report that sol–gel process based on chelating of citric acid is also effective in fabricating NiCo and Ni3Fe nanoalloys under N2 or H2 atmosphere during heating treatment. With the introducing of surfactant, the average grain size of the nanoalloys is less than 10nm and the grain size distribution is narrow. The formation of nanoalloys with equilibrium ordered phase rather than metastable disordered phase is confirmed by the occurrence of superlattice diffraction rings obtained by selected area electron diffraction. The Ni3Fe nanoalloy shows typical ferromagnetic behavior at room temperature.