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Naturally occurring tungsten consists of four stable isotopes (182 W, 183 W, 184 W, and 186 W) and one very long-lived radioisotope, 180 W. Theoretically, all five can decay into isotopes of element 72 by alpha emission, but only 180 W has been observed to do so, with a half-life of (1.8 ± 0.2) × 10 18 years; [36] [37] on average, this yields ...
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For the production of the tungsten heavy alloy, binder mixtures of nickel and iron or nickel and copper are widely used. The tungsten content of the alloy is normally above 90%. The diffusion of the binder elements into the tungsten grains is low even at the sintering temperatures and therefore the interior of the grains are pure tungsten. [18]
Congo is a major source of tin, tantalum and tungsten, so-called 3T minerals used in computers and mobile phones. But some artisanal mines are run by armed groups involved in massacres, rapes and ...
The discovery of superhard tungsten tetraboride is further evidence for the promising design approach of covalently bonding incompressible transition metals with boron. While WB 4 was first synthesized and identified as the highest boride of tungsten in 1966, [52] it was only recognized as an inexpensive superhard material in 2011. [53]
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Ferrotungsten is relatively expensive, with the prices around $31–44 per kilogram of contained tungsten. [4] During World War 2, over 21,000,000 lb of Ferro-tungsten and other ferroalloys were shipped to Russia on lend-lease. [3] The cost was more than $12,000,000. Ferrotungsten comes from rich ore raw materials primarily of wolframite or ...
Tungsten steel is any steel that has tungsten as its alloying element with characteristics derived mostly from the presence of this element (as opposed to any other element in the alloy). Common alloys have between 2% and 18% tungsten by weight along with small amounts of molybdenum and vanadium which together create an alloy with exceptional ...