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An alloy is a mixture of chemical elements, which forms an impure substance (admixture) that retains the characteristics of a metal. An alloy is distinct from an impure metal in that, with an alloy, the added elements are well controlled to produce desirable properties, while impure metals such as wrought iron are less controlled, but are often ...
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
A refractory metal is a metal that is very resistant to heat and wear. Which metals belong to this category varies; the most common definition includes niobium, molybdenum, tantalum, tungsten, and rhenium as well as their alloys. They all have melting points above 2000 °C, and a high hardness at room temperature. Several compounds such as ...
Nickel is preeminently an alloy metal, and its chief use is in nickel steels and nickel cast irons, in which it typically increases the tensile strength, toughness, and elastic limit. It is widely used in many other alloys, including nickel brasses and bronzes and alloys with copper, chromium, aluminium, lead, cobalt, silver, and gold ( Inconel ...
To achieve these improved properties the metal may require specific heat treating, combined with strict cooling protocols. Although alloy steels have been made for centuries, their metallurgy was not well understood until the advancing chemical science of the nineteenth century revealed their compositions. Alloy steels from earlier times were ...
Copper alloys are widely used in the production of coinage; seen here are two examples – post-1964 American dimes, which are composed of the alloy cupronickel [55] and a pre-1968 Canadian dime, which is composed of an alloy of 80 percent silver and 20 percent copper.
As with almost all aluminium alloys, a distinction is made between wrought alloys for rolling and forging and cast alloys for casting. The copper content is usually between 3 and 6%. Between 0.3% and 6% the alloys are regarded as not weldable or very difficult to weld (by fusion welding), with higher copper contents they become weldable again.
Some silicon metal was also used as an alloying agent with iron. On the basis of silicon content, net production of ferrosilicon and miscellaneous silicon alloys in the US was 148,000 t in 2008. China is the major supplier, which in 2008 produced more ferrosilicon (4.9 Mt) than the rest of the world combined.