A niobium alloy is one in which the most common element is niobium.

Alloys used for the production of other alloys edit

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 edit

 
Niobium–tin superconducting wire from the ITER fusion reactor, which is currently under construction.

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 edit

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 edit

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 edit

  1. ^ 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)
  2. ^ 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.
  3. ^ 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.