- Niobium alloy
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A niobium alloy is one in which the most common element is niobium.
Contents
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 (30T for Nb3Sn, 15T 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. Usage field of rivet in aircraft ; blind rivet used in wing of aircraft fastening and for wheels of aircraft.
Refractory alloys
Niobium-1% zirconium is used in rocketry and in the nuclear industry; the space nuclear reactor presented in http://www.ornl.gov/~webworks/cppr/y2001/rpt/121399.pdf is predominantly made of this alloy. It is regarded as a low-strength alloy.
C-103, which is 89% Nb, 10% Hf and 1% Ti, was used for the rocket nozzle of the Apollo service module; 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 1650C with acceptable strength, though are expensive and hard to form.
Niobium alloys in general are inconvenient to weld: both sides of the weld need to be protected with a stream of pure inert gas, since hot niobium reacts 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. Blind rivet used in wing of aircraft fastening
References
http://www.wahchang.com/pages/products/data/niobium/Niobium.pdf
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