Wikipedia:Today's featured article/April 16, 2009



Niobium is a chemical element with symbol Nb and atomic number 41. A rare, soft, grey, ductile transition metal, niobium is found in the minerals pyrochlore (the main source for niobium) and columbite. Niobium has similar physical and chemical properties to another element, tantalum, and the two are therefore difficult to distinguish. The German chemist Heinrich Rose determined in 1846 that tantalum ores contain a second element, which he named niobium, after Niobe from Greek mythology. It was not until the early 20th century that niobium was first used commercially. Brazil is the leading producer of niobium and ferroniobium, an alloy of niobium and iron. Niobium is used mostly in alloys, the largest part in special steel such as that used in gas pipelines. Although alloys contain only a maximum of 0.1%, that small percentage improves the strength of the steel. The temperature stability of niobium-containing superalloys is important for its use in jet engines and rocket engines. Niobium is used in various superconducting materials. These superconducting alloys, also containing titanium and tin, are widely used in MRI scanners. Other applications of niobium include its use in welding, nuclear industries, electronics, optics, numismatics and jewellery. In the last two applications, niobium's low toxicity and ability to be coloured by anodisation are particular advantages. (more...)

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