Facile synthesis of Nb–Al alloy powders via sodiothermic reduction in molten salts

Abstract

Nb–Al intermetallic powders were synthesized via sodiothermic reduction process in NaCl–CaCl2 molten salts using Nb2O5 and Al2O3 as raw materials. The as-prepared samples were characterized by X-ray diffraction and scanning electron microscopy. The homogeneity of Nb2O5/Al2O3 composites was investigated by mechanical ball-milling process using Nb2O5 and Al2O3 with heavy aggregation at the different times. It was found that the homogeneous Nb2O5/Al2O3 composites were obtained after ball-milling for 10h. Using these homogeneous Nb2O5/Al2O3 composites with a molar ratio of 4:1, 1:3 and 1:1 as precursors, Nb–Al intermetallic powders of Nb3Al, NbAl3 and the mixture of Nb2Al and NbAl3 were produced in NaCl–CaCl2 molten salts at 700°C. In comparison, the Nb2Al/NbAl3 composites were also fabricated using single-phase Na2NbAlO5 synthesized using Nb2O5 and NaAlO2 as raw materials in molten NaCl–KCl, which is ascribed to the homogenous distribution of Nb and Al in the multi-phase oxides.