Niobium is a light grey, crystalline, ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and its ductility is comparable to iron. A niobium alloy is one in which niobium is the most prevalent element.

Applications

Alloys Used in Producing Other Alloys

The most common commercial niobium alloys are ferroniobium and nickel-niobium, produced by thermite reduction of the appropriate oxide mixtures. These are not used directly as engineering materials but serve as a convenient source of niobium for specialist steels and nickel-based superalloys — going via an iron-niobium or nickel-niobium intermediate avoids the difficulties associated with niobium’s high melting point.

Superconducting Alloys

Niobium-tin and niobium-titanium are essential alloys for industrial superconductor applications, remaining superconducting even in very high magnetic fields (30T for Nb3Sn, 15T for NbTi). Roughly 1,200 tons of NbTi are used in the magnets of the Large Hadron Collider, while Nb3Sn is used in the windings of almost all hospital MRI machines.

Aerospace Rivets

Niobium-titanium alloy — the same composition used for superconducting wire — is used for rivets in the aerospace industry. It is easier to form than commercially-pure titanium, and retains strength better at elevated temperatures above 300°C.

Refractory Alloys

Niobium-1% zirconium is used in rocketry and the nuclear industry, and is generally regarded as a low-strength alloy suited to specific high-temperature, low-load applications.