Effects of Porosity and Ni/Al Molar Ratio in Ni–Al Oxide Precursors on Porous Intermetallic Nickel Aluminide Nanopowders Prepared by Chemical Route

摘要

It is challenging to prepare intermetallic Ni–Al nanopowders via chemical processes due to the difficulty in reducing Al-based oxides. Previously, we successfully obtained the single phase porous nanopowders of Ni_(3)Al and NiAl from the low porosity oxide precursors in molten LiCl–CaH_(2) at 600°C. In this study, we examined the effects of porosity and the Ni/Al molar ratio of the oxide precursors on the BET surface areas and phases of the final Ni–Al nanopowders. The results showed that the porosity was not reflected in the final products, but the Ni/Al molar ratio defined the crystal structures. The intermetallic Ni_(5)Al_(3) phase was not obtained at all, possibly due to the low rate of formation, whereas pure intermetallic Ni_(3)Al and NiAl phases were obtained separately without any impurity phases.