Niobium (Nb) has the smallest specific gravity in refractory metals. Compared with other refractory metals, niobium alloy has higher specific strength, excellent plasticity, workability and weldability. At the same time, it also has small thermal neutron absorption cross section and resistance to liquid metal erosion. As a high temperature structural material, niobium alloy has good high temperature strength and good formability, and has been widely used in the aerospace field in the past few decades. However, with the development of aerospace technology and national defense industry, high-temperature structural materials are required to withstand high stresses in high temperature and oxidation environments above 1200 ℃.
In order to improve the high temperature strength of niobium alloy, the traditional high strength niobium alloy is to add a large number of high melting point refractory metals (such as W, Mo, Ta and Hf, etc.) in niobium for solid solution strengthening, and improve the service temperature of niobium alloy. Due to the high degree of alloying, the lattice has serious distortion, the plasticity of niobium alloy is seriously decreased, the processing performance of the material is poor, the yield is very low, and the single solution strengthening mechanism is difficult to greatly improve the high temperature mechanical properties of niobium alloy. At the same time, due to the introduction of a large number of elements such as W, Mo, Ta and Hf, the specific gravity of niobium alloy increases and the high temperature oxidation resistance is seriously deteriorated, which is not conducive to the application in aerospace. Another kind of high strength niobium alloy is NbC dispersion strengthened niobium alloy, although NbC has a high melting point, high hardness and high elastic modulus, can significantly improve the high temperature strength of niobium alloy, but NbC polarization is serious, so that the plasticity of the material is seriously reduced, processing and forming difficulties, and reduce the reliability of the use of materials.
An Nb-Ti-Ta-C alloy bar is provided. The tensile strength of the alloy bar at room temperature is 1060MPa ~ 1205MPa, the elongation at room temperature is 13% ~ 20%, and the tensile strength at 1400℃ is 312MPa ~ 415MPa. The loss of the alloy bar after oxidation for 100h in the air environment at 1400℃ is 0.18mg/cm2 ~ 0.093mg/cm2. It is proved that the Nb-Ti-Ta-C alloy bar has excellent high temperature strength, good room temperature plasticity and high temperature oxidation resistance, and can be used in ultra-high temperature air environment.
