Synthesis of Nb/Nb5Si3 Nanocomposite and Nb5Si3 Intermetallic by Self-propagating High-temperature Synthesis

In this study, Nb5Si3 and Nb/Nb5Si3 nanocomposite were fabricated by self-propagating high-temperature synthesis (SHS). The mixture of Nb and Si powders as the starting materials were mixed according to Nb5Si3 stoichiometric composition with 0 and 20 mol% additional Nb. Then, the green pellets were preparedby uniaxial cold pressing of the mixed powders mixture. Green compacts were placed in a combustion reactor with argon atmosphere and were synthesized. For the investigation of pre-milling effect on synthesis, the mixture of Nb and Si powders as the starting materials were milled according to Nb5Si3 stoichiometric composition with 0 and 20 mol% additional Nb, at 6 and 10 h, with ball-to-powder ratio 10:1. Then, the green pellets were prepared by uniaxial cold pressing of the as-milled powders mixture and were placed inside reactor and were synthesized. The mixed and synthesized samples were characterized by XRD, SEM, EDS, TEM and AAS analytical techniques. The results showed that, α-Nb5Si3 and β-Nb5Si3 by SHS method and without pre-milling and hexagonal Nb5Si3 by SHS method with pre-milling were synthesized. By increasing in milling time before the combustion reaction, the crystallites size of the end product was reduced and nanostructured product was produced.