Effect of C Addition on the Microstructure and Fracture Properties of In Situ Laminated Nb/Nb₅Si₃ Composites

//Nb_ss and α-Nb₅Si₃ phases were detected. Meanwhile, Nb₂C was observed, and the crystal forms of Nb₅Si₃ changed in the C-doped composites. Furthermore, micron-sized and nano-sized Nb₂C particles were found in the Nb_ss layer. The orientation relationship of Nb₂C phase and the surrounding Nb_ss was [001]_Nbss//[010]_Nb2C, (200) _Nbss//(101) _Nb2C. Additionally, with the addition of C, the compressive strength of the composites, at 1400 °C, and the fracture toughness increased from 310 MPa and 11.9 MPa·m^1/2 to 330 MPa and 14.2 MPa·m^1/2, respectively; the addition of C mainly resulted in solid solution strengthening.