Niobium alloy
A niobium alloy is one in which the most common element is niobium.
Alloys used for the production of other alloys
The most common commercial niobium alloys are ferroniobium and nickel-niobium, produced by thermite reduction of appropriate mixtures of the oxides; these are not usable as engineering materials, but are used as convenient sources of niobium for specialist steels and nickel-based superalloys. Going via an iron-niobium or nickel-niobium alloy avoids problems associated with the high melting point of niobium.
Superconducting alloys
Niobium-tin and Niobium-titanium are essential alloys for the industrial use of superconductors, since they remain superconducting in high magnetic fields (30 T for Nb3Sn, 15 T for NbTi); there are 1200 tons of NbTi in the magnets of the Large Hadron Collider, whilst Nb3Sn is used in the windings of almost all hospital MRI machines.
Aerospace rivets
Niobium-titanium alloy, of the same composition as the superconducting one, is used for rivets in the aerospace industry; it is easier to form than CP titanium, and stronger at elevated (> 300°C) temperatures.
Refractory alloys
Niobium-1% zirconium is used in rocketry and in the nuclear industry. It is regarded as a low-strength alloy.[1][2]
C-103, which is 89% Nb, 10% Hf and 1% Ti, is used for the rocket nozzle of the Apollo service module and the Merlin vacuum[3] engines; it is regarded as a medium-strength alloy.
High-strength alloys include C-129Y (10% tungsten, 10% hafnium, 0.1% yttrium, balance niobium), Cb-752 (10% tungsten, 2.5% zirconium), and the even higher strength C-3009 (61% niobium, 30% hafnium, 9% tungsten); these can be used at temperatures up to 1650°C with acceptable strength, though are expensive and hard to form.
Niobium alloys in general are inconvenient to weld: both sides of the weld must be protected with a stream of inert gas, because hot niobium will react with oxygen and nitrogen in the air. It is also necessary to take care (e.g. hard chrome-plating of all copper tooling) to avoid copper contamination.
References
- ^ Yoder, G.; Carbajo, J.; Murphy, R.; Qualls, A.; Sulfredge, C.; Moriarty, M.; Widman, F.; Metcalf, K.; Nikitkin, M. (September 2005). "TECHNOLOGY DEVELOPMENT PROGRAM FOR AN ADVANCED POTASSIUM RANKINE POWER CONVERSION SYSTEM COMPATIBLE WITH SEVERAL SPACE REACTOR DESIGNS" (PDF).
{{cite journal}}: Cite journal requires|journal=(help) - ^ Roche, T. (1 October 1965). Evaluation of Niobium-Vanadium Alloys for Application in High-Temperature Reactor Systems (PDF) (Technical report). Oak Ridge National Laboratory. doi:10.2172/4615900. ORNL-TM-1131. Archived from the original (PDF) on 7 January 2014. Retrieved 7 January 2014.
- ^ Hafnium (PDF). 6th Annual Cleantech & Technology Metals Conference. Toronto: Alkane Resources Ltd. 15–16 May 2017. Archived from the original (PDF) on 2017-09-18. Retrieved 2020-12-06.