Mechanical properties of multiphase Nb–Si–Fe in situ composites

Nb–xSi–2Fe (x = 3, 6, 10, 16 at.%) in situ composites consisting of an Nb solid solution and the intermetallic phases Nb3Si, Nb5Si3 and Nb4Fe3Si5 were synthesized by hot pressing sintering to yield a fine microstructure with all four phases being in micron range. Fracture toughness of these composites at room temperature increase from 10.2 to 14.6 MPa m1/2 with content of Si from 16 to 3 at.%. The Nb4Fe3Si5 phase contributes to improve the fracture toughness of these composites. The tensile properties of these composites at elevated temperature were evaluated in vacuum at 1300 °C with strain rate of 2.31 × 10−4 s−1. These composites displayed large ductility and good mechanical strength.