Synthesis and characterization of nanocrystalline iron aluminide particles

In this work, we report the synthesis of intermetallic FeAl nanoparticles using the laser vaporization controlled condensation technique. Nanoparticles of iron aluminides are expected to enhance the room temperature ductility and the high temperature strength of these materials. The nanoparticles have an average particle diameter between 6 and 9 nm. Measurements of the d-spacing from X-ray (XRD) and electron diffraction studies confirm that the nanoparticles have the same crystal structure (B2) as the bulk FeAl. High-resolution TEM reveals that the nanoparticles consist of a crystalline core encased within a ≈1 nm amorphous layer formed upon the exposure of the particles to air. XPS results indicate that the naoparticles have an Al-rich surface composition, which supports the assumption that the surface coating is Al oxide. The FeAl oxide nanoparticles prepared in the presence of O2 have the hercynite FeAl2O4 composition and exhibit a different XRD pattern from that of the surface-oxidized FeAl nanoparticles. The current results demonstrate that, by controlling the experimental conditions, it is possible to prepare a variety of intermetallic nanoparticles with selected size, morphology and composition. These particles can serve as the building blocks for advanced, high performance materials for several industrial and technological applications.