Niobium, also known as columbium, is a rare exotic soft metal that was discovered in 1801. It looks like steel or, when polished, it looks like platinum. Niobium resists corrosion and can maintain its qualities at very high temperatures (the melting point is 2,468°C).

The primary mineral, from which niobium is obtained, is known as pyrochlore (NaCaNb₂O₆F). It is recovered primarily by a physical processing technology to give a concentrate ranging from 50% to about 60% niobium oxide. The world consumes nearly 40,000 tonnes of Nb₂O₅ a year according to Roskill, a metals market research organisation. In the last decade, demand for Nb₂O₅ has doubled.

Niobium Properties

Atomic Number:	41
Atomic Weight:	92.906
Melting Point (°C):	2468
Boiling Point (°C):	4927
Density (g/m³):	8.57
Tensile Strength (20°C, MPa):	Recrystallised Sheet 250 MPa Cold Worked Sheet 600 MPa
Elastic Modulus (GPa):	110.32

Some 89% of the consumption of niobium is dedicated to the production of steel, while 9% is used in the production of superalloys and the final 2% is being used in the development of superconductor applications and medical uses. Niobium’s numerous applications are growing steadily!

Niobium is a metal with unique properties. When used as an additive, in the production of steel, niobium imparts an increased level of elasticity, improved formability and resistance to corrosion. It is in the form of ferroniobium that niobium is used in the high-end steel applications. The following figure illustrates the engineering effects of the addition of very small quantities of niobium to steel.

Summary of mill-trail results for hot-rolled Nb-Ti sheet steels

The large diameter pipelines for the transmission of oil and gas is the most important item produced from plate steel. Another area of application of niobium microalloying includes its use for shipbuilding and offshore platforms. High strength niobium microalloyed steel is increasingly used as critical components of bridges, viaducts, and other structures.

Researchers and metallurgists have forwarded the use of aluminium as the replacement for steel in the production of the automobile chassis. The steel industry responded by introducing titanium-niobium steel, which is lighter than normal steel. Not only did this allow car manufacturers to reduce the weight of the chassis, but the cost have been less than aluminium.

As shown in the following table for instance, a 20-40% reduction in the car weight can be obtained by adding niobium to steel in the following products. A significant reduction of CO₂ emissions into the atmosphere would result.

Superalloys, designed to function for extended periods of time in highly corrosive environments above 650ºC, represent the second largest market for niobium after the steel industry. Superalloys constitute about 9% of the global market for niobium. Niobium-based alloys are used as refractory materials for aerospace applications since they have excellent high temperature strength above 1300ºC and readily accept coatings to protect against oxidation. There are hundreds of different superalloys, but one of the most important ones is Inconel 718. It is a nickel-based alloy containing 5.3% to 5.5% by weight of niobium and is essential in the safe operation of modern jet engines. Another important alloy is C-103 (a niobium-based hafnium-titanium alloy) and it is mainly used in rocket thrusters and nozzles.

Alloying niobium to other elements can produce materials with highly desirable engineering properties. For example, 1200 megapascals (MPa) was achieved using a metastable aluminum-niobium binary at Ames lab in the USA. In contrast, a commercial aluminum alloy typically fractures at 300 or 400 MPa.

Niobium has long been known to exhibit superconducting properties. Although pure niobium is used in particle accelerators, the most important commercial harnessing of these superconducting properties are in niobium-titanium and niobium-tin alloys. These alloys are used in MRI (Magnetic Resonance Imaging) and NMR (Nuclear Magnetic Resonance) machines.

Zirconium-2.5% niobium alloy is another application and is used in heavy water reactors. The high strength permits thin walls thus allowing for better neutron economy. US Navy nuclear submarines also use this alloy for their reactors.

High purity niobium oxide is used in the manufacture of ceramics, which includes ceramic capacitors for electronics. In optical lenses, it increases the refractive index, which results in lighter lenses.