2004 Volume 45 Issue 12 Pages 3264-3271
Design of two-phase alloys consisting of niobium solid solution (A2) and α-Nb5Si3 (D8l) phases in the Nb-Ti-Si ternary system is pursued for ultra-high temperature structural applications. Compositional and annealing conditions are determined for the formation of A2/D8l lamellar microstructure via eutectoid decomposition of Nb3Si (tP32) phase in the Nb-Si binary and Nb-Ti-Si ternary system. Addition of titanium is found to result in increased room temperature toughness, but decreased high temperature strength. Enhancement of mechanical properties is achieved by applying the directional solidification technique. Mechanical properties of the alloys are discussed from microstructural point of view.