Microstructures and mechanical properties of cast Nb–Ti–Si–Zr alloys

The effect of Zr addition on the microstructures and mechanical properties of cast Nb–22Ti–16Si–xZr (x = 0–4) alloys was investigated. The results show that the Zr addition leads to coarseness of primary Nbss phase promotes formation and coarseness of Nbss and γ(Nb)5Si3 lamellar eutectic structure. In addition, the Zr addition increases the hardness of Nbss and (Nb)3Si phases. The yield strength at room temperature of the alloys improves with increasing Zr content. The fracture strain reaches a peak value in 3 at.% Zr content, and then drops with the increase of Zr content. The high temperature strength decreases first and reaches a minimal value in 3 at.% Zr content, and then increases again. These variations are attributed to the microstructure and composition changes of the alloys with increasing Zr content.