Electrochemical preparation of the Fe-Ni36 Invar alloy from a mixed oxides precursor in molten carbonates

The Fe-Ni36 alloy was prepared via the one-step electrolysis of a mixed oxides precursor in a molten Na2CO3-K2CO3 eutectic melt at 750 degrees C, where porous Fe2O3-NiO pellets served as the cathode and the Ni10Cu11Fe alloy was an inert anode. During the electrolysis, NiO was preferentially electro-reduced to Ni, then Fe2O3 was reduced and simultaneously alloyed with nickel to form the Fe-Ni36 alloy. Different cell voltages were applied to optimize the electrolytic conditions, and a relatively low energy consumption of 2.48 kWhkg(-1) for production of FeNi36 alloy was achieved under 1.9 V with a high current efficiency of 94.6%. The particle size of the alloy was found to be much smaller than that of the individual metal. This process provides a low-carbon technology for preparing the Fe-Ni36 alloy via molten carbonates electrolysis.