To improve the mechanical properties of Nb–Si alloy, the influence of C addition on microstructural evolution and mechanical properties of Nb–16Si–24Ti based alloys is studied. Results show that with the C content increase, the microstructure of Nb–16Si–24Ti-xC transforms from hypoeutectic structure to nearly eutectic structure, and the phase constitutions transform from Nbss + (Nb, Ti)₃Si to Nbss + γ-(Nb, Ti)₅Si₃. The microstructure transforms into fully eutectic structure and TiC phase is precipitated by addition of 4 at.% C. The element C is mainly dissolved in the Nbss phase, and the nanoindentation hardness of Nbss phase obviously increases with the increasing of C content, which is attributed to the solid solution strengthening by C addition. The fracture toughness increases from 6.3 MPa m^1/2 to 14.9 MPa m^1/2, as the C content increases from 0 at.% to 3 at.%, since with the C content increase, the c/a ratio decreases, the Nbss phase content increases, and the Nbss phase becomes more continuous. The addition of 4 at.% C induces the formation of TiC phase in the matrix, and thus decreases the fracture toughness.

为了改善Nb-Si合金的力学性能，研究了C的添加对Nb-16Si-24Ti基合金的组织演变和力学性能的影响。结果表明，随着C含量的增加，Nb–16Si–24Ti- x C的微观结构从亚共晶结构转变为近共晶结构，相结构从Nbss +（Nb，Ti）₃ Si转变为Nbss +γ-（ Nb，Ti）₅ Si ₃。通过添加4at。％的C，组织转变为完全的共晶结构，并析出TiC相。元素C主要溶解在Nbss相中，并且随着C含量的增加，Nbss相的纳米压痕硬度明显增加。归因于通过添加C固溶强化。随着C含量从0at。％增加到3at。％，断裂韧性从6.3 MPa m ^1/2增加到14.9 MPa m ^1/2，因为随着C含量的增加，c / a比降低， Nbss相含量增加，Nbss相变得更连续。添加4 at。％C会诱导基体中TiC相的形成，从而降低断裂韧性。