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Most metal borides are hard; [41] however, a few stand out among them for their particularly high hardnesses (for example, WB 4, [42] [43] RuB 2, OsB 2 and ReB 2). These metal borides are still metals and not semiconductors or insulators (as indicated by their high electronic density of states at the Fermi Level ); however, the additional ...
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Manufacturers use its alloys with platinum, iridium, and other platinum-group metals to make fountain pen nib tipping, electrical contacts, and in other applications that require extreme durability and hardness. [12] Osmium is among the rarest elements in the Earth's crust, making up only 50 parts per trillion . [13] [14]
As in the cases of other refractory metals, the hardest known compounds of tantalum are nitrides and carbides. Tantalum carbide, TaC, like the more commonly used tungsten carbide, is a hard ceramic that is used in cutting tools. Tantalum(III) nitride is used as a thin film insulator in some microelectronic fabrication processes. [38]
This is a list of named alloys grouped alphabetically by the metal with the highest percentage. Within these headings, the alloys are also grouped alphabetically. Within these headings, the alloys are also grouped alphabetically.
The strength and high-temperature stability of refractory metals make them suitable for hot metalworking applications and for vacuum furnace technology. Many special applications exploit these properties: for example, tungsten lamp filaments operate at temperatures up to 3073 K, and molybdenum furnace windings withstand 2273 K.
Amongst the alloys made of gold, silver, and copper, the hardest is the 18.1 K pink gold (75.7% gold and 24.3% copper). An alloy with only gold and silver is the hardest at 15.5 K (64.5% gold and 35.5% silver). During ancient times, due to impurities in the smelting process, gold frequently turned a reddish color.
One of the largest bullion coins in the world was the 10,000-dollar Australian Gold Nugget coin minted in Australia, which consists of a full kilogram of 99.9% pure gold. In 2012, the Perth Mint produced a 1-tonne coin of 99.99% pure gold with a face value of $ 1 million AUD, making it the largest minted coin in the world with a gold value of ...