Direct synthesis of Nb–Al intermetallic nanoparticles by sodiothermic homogeneous reduction in molten salts

• Nb or Al powders were synthesized using Nb2O5 or Al2O3 as raw materials.
• Nb–Al intermetallics were synthesized by co-reduction of homogeneous systems.
• Nb2Al/NbAl3 composites were also prepared from homogeneous systems.
• The obtained Nb–Al alloy powders were systematically characterized.
• Influence of reaction temperature on the size of powders was investigated.

Nb–Al intermetallic nanoparticles were directly synthesized via sodiothermic reduction process in molten salts using NbCl5 and AlCl3 as the raw materials. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The NbCl5 and AlCl3 were dissolved in LiCl–KCl–CaCl2 or LiCl–KCl–NaCl–CaCl2 molten salts forming a homogeneous system. It was found that a series of intermetallic nanoparticles, such as Nb3Al, Nb2Al, NbAl3 and Nb2Al/NbAl3, were successfully synthesized at low temperature of 350–500 °C using the homogeneous molten salt systems. The phase transformations of Nb3Al, Nb2Al and NbAl3, were achieved via the controllable variation of molar ratio of Nb to Al. Furthermore, the influence of the reaction temperature on the particle size of the intermetallic nanoparticles was also investigated.