Synthesis of nanocrystalline NbAl3 by mechanical and field activation

The mechanically-activated, field-activated, and pressure-assisted synthesis (MAFAPAS) process, which combines the simultaneous synthesis and densification of nanophase materials, was utilized to produce nanocrystalline NbAl3 material from Nb+3Al mechanically activated powders. Nb+3Al elemental powders were co-milled for a short time in a specially designed planetary ball mill to obtain nanoscale distributed reactants but to avoid the formation of any product phases. These were then subjected to high AC currents (1500–1650 A) and uniaxial pressures (56–84 MPa). Under these conditions, a reaction is initiated by field activation and completed within a short period of time (3–6 min). Using XRD analyses, the MAFAPAS end-product was identified as NbAl3. Back-scattered electron SEM observations coupled with EDXS analyses showed the presence of small amounts of alumina precipitates together with unreacted niobium in the NbAl3 matrix. The end-product relative density ranged from 85 to 96%. The NbAl3 crystallite size, determined by XRD line-broadening analysis using the Langford method, was in the range of 57–150 nm.