Niobium and its Alloys
Niobium was first separated in the year of 1801. This metal has lowest melting point among five refractory element (that means 2468oC). Its density at 8570 kg/m3 is also lowest. Nb is utilized as alloying, element for stabilized stainless steels, microalloyed steels, & as solid solution alloying addition to various nickel based super alloys. Inconel 718 is one such alloy. Nb alloys are utilized for aerospace & missile application because Nb has low density and high strength at elevated temperature. It is utilized in superconducting alloy with Ti. Various alloys of Nb are prepared by adding up such element as Zr, Ti, Hf and Ta. The alloys are built by vacuum-arc-melting.
The C 103 alloy (Nb-10%, Hf, 1% Ti, 0.75% Zr) was made to replace weaker Nb alloys while retaining formability & welding properties. This alloy is coated for oxidation resistance for use in rocket applications needing moderate strength at temperatures of approx 100 to 1370oC. Some of alloys which have better strength than that of C 103 alloy at elevated temperatures are : FS85 (Nb-27.5% Ta, 11% W, 1% Zr), C129Y (Nb-10% W, 10% Hf, 0.15% Y), and Cb752 (Nb-10% W, 2.5% Zr). All of three alloys might be fabricated, are thermally stable and might be protected against oxidation by coating. These alloys with protection from oxidation discover use in leading edges, gas turbines, rocket nozzles, and guidance structure for reentry vehicles.