FeAl-B composites with nanocrystalline matrix produced by consolidation of mechanically alloyed powders.

Mechanically alloyed composite powders with equiatomic Fe–Al stoichiometry and with the addition of 5, 10, 20 and 30 vol% of B were subjected to consolidation. For this purpose, hot-pressing at 800 °C under the pressure of 7.7 GPa for 180 s was applied. A reference FeAl sample was prepared using the same procedure as these from the composite powders. The produced bulk materials were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy as well as characterised by hardness, density and open porosity measurements. For the compositions containing 5, 10 and 20% of B, it was possible to obtain composites with the nanocrystalline FeAl intermetallic matrix reinforced with homogenously distributed fine boron particles. For the material containing 30% of B, the boron particles were distributed in a two-phase matrix consisting of the dominant nanocrystalline FeAl intermetallic and minor amorphous phases. The density of the composite samples is in the range of 5.31 ÷ 4.57 g/cm3, which is lower than that of the FeAl reference sample, and decreases with the increase of B content. The hardness of the composite samples is in the range of 10.75 ÷ 12.1 GPa, is higher than that of the intermetallic FeAl reference sample (9.84 GPa), and increases with the increase of B content. To the best of our knowledge, the FeAl-B composites with nanocrystalline intermetallic matrix were produced for the first time. • This is the first production of bulk nanocrystalline matrix FeAl–B composites. • The hardness of the composites is of 10.75 ÷ 12.1 GPa, depending on B content. • The hardness of the composites is higher than that of nanocrystalline FeAl alloys. • The density of the composites is of 5.31 ÷ 4.57 g/cm3, depending on B content. • The density of the composites is lower than that of nanocrystalline FeAl alloy. [ABSTRACT FROM AUTHOR]