Magnetic properties of carbon-encapsulated Fe–Ni alloy nanocomposites

• Fe-Ni@C alloy nanoparticles were fabricated using melamine as carbon source.
• Their structure, morphology and magnetic properties were researched.
• The highest MS of Fe-Ni@C alloy is 132 emu/g.

Carbon-encapsulated Fe–Ni alloy nanoparticles (Fe–Ni@C) have been fabricated with different Ni/Fe ratio by an solid-state route using melamine as carbon source. The structure and morphology of Fe–Ni@C nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The XRD characterization results reveal that all products are alloys with no carbide impurity. The TEM and HRTEM observations show that the alloy nanoparticles are encapsulated in carbon shells. Additionally, the reactions involved in the syntheses are speculated. The variation of magnetic properties of Fe–Ni@C with Ni/Fe has been discussed according to the room temperature VSM measurement results.