Preparation of Ni-Al alloys at reduced temperature for fuel cell applications

Ni-Al alloys have been fabricated from the physical mixture of nickel and aluminum powders at temperatures below the melting point of aluminum using AlCl ₃ vapor as an activator. Pure Ni ₃Al intermetallic compound has been synthesized from the Ni-Al powder mixtures containing 15 wt% aluminum at 600 °C. From the powder mixture containing 5 wt% aluminum, a compound consisting of Ni-Al solid solution and Ni ₃Al was produced at 600 °C, but this compound was converted entirely to a Ni-Al solid solution after annealing at 700 °C. The particle size and morphology of the Ni-Al solid solution were not greatly different from original nickel powders. It was observed that oxidation resistance was significantly enhanced by alloying of nickel with aluminum. The Ni-Al alloys synthesized in this study can be used as anode materials for high-temperature fuel cells which need improved resistance toward creep, sintering and redox cycling.