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Alloy

 

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Alloy



 
 
An alloy is a partial or complete solid solution
Solid solution

A solid solution is a solid-phase solution of one or more soluble in a solvent. Such a mixture is considered a solution rather than a Chemical compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single wiktionary:Homogeneous phase ....
 of one or more elements
Chemical element

A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its atomic nucleus. The term is also used to refer to a pure chemical Chemical substance composed of atoms with the same number of protons....
 in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal (heat treatment) history.






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Steel Wire Rope
An alloy is a partial or complete solid solution
Solid solution

A solid solution is a solid-phase solution of one or more soluble in a solvent. Such a mixture is considered a solution rather than a Chemical compound when the crystal structure of the solvent remains unchanged by addition of the solutes, and when the mixture remains in a single wiktionary:Homogeneous phase ....
 of one or more elements
Chemical element

A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its atomic nucleus. The term is also used to refer to a pure chemical Chemical substance composed of atoms with the same number of protons....
 in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal (heat treatment) history. Alloys usually have different properties from those of the component elements.

Alloying one metal with other metal(s) or non metal(s) often enhances its properties. For instance, steel
Steel

Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight , depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten....
 is stronger than iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
, its primary element. The physical properties, such as density
Density

The density of a material is defined as its mass per unit volume. The symbol of density is ....
, reactivity
Reactivity

Reactivity refers to the Reaction rate at which a chemical substance tends to undergo a chemical reaction in time. In pure chemical compounds, reactivity is regulated by the physical properties of the sample....
, Young's modulus
Young's modulus

In solid mechanics, Young's modulus is a measure of the stiffness of an isotropic elastic material. It is also known as the Young modulus, modulus of elasticity, elastic modulus or tensile modulus....
, and electrical
Electrical conductivity

Electrical conductivity or specific conductance is a measure of a material's ability to electrical conduction an electric current. When an electrical potential difference is placed across a conductor, its movable charges flow, giving rise to an electric current....
 and thermal conductivity
Thermal conductivity

In physics, thermal conductivity, , is the List of materials properties of a material that indicates its ability to conduct heat. It appears primarily in Heat conduction#Fourier's law for heat conduction....
, of an alloy may not differ greatly from those of its elements, but engineering properties, such as tensile strength
Tensile strength

Tensile strength , or is the Stress at which a material breaks or permanently deforms. Tensile strength is an Intensive and extensive properties and, consequently, does not depend on the size of the test specimen....
 and shear strength
Shear strength

Shear strength in engineering is a term used to describe the strength of a material or component against the type of Yield or structural failure where the material or component fails in Shearing ....
 may be substantially different from those of the constituent materials. This is sometimes due to the sizes of the atom
Atom

|-! bgcolor=gray | Properties|-||}The atom is a basic unit of matter consisting of a dense, central atomic nucleus surrounded by a electron cloud of electric charge electrons....
s in the alloy, since larger atoms exert a compressive force on neighboring atoms, and smaller atoms exert a tensile force on their neighbors, helping the alloy resist deformation. Alloys may exhibit marked differences in behavior even when small amounts of one element occur. For example, impurities in semi-conducting ferromagnetic alloys lead to different properties, as first predicted by White, Hogan, Suhl, Tian Abrie and Nakamura. Some alloys are made by melting and mixing two or more metals. Brass
Brass

Brass is any alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. In comparison, bronze is principally an alloy of copper and tin....
 is an alloy made from copper and zinc. Bronze
Bronze

Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive, but sometimes with other chemical element such as phosphorus, manganese, aluminium, or silicon....
, used for bearings
Bearing (mechanical)

A bearing is a device to allow constrained relative motion between two parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle....
, statue
Statue

A statue is a sculpture in the round representing a person or persons, an animal, or an event, normally full-length, as opposed to a Bust , and at least close to life-size, or larger....
s, ornaments
Ornament (architecture)

In architecture, ornament is a decorative detail used to embellish parts of a building or interior furnishing. Ornament can be carved from stone, wood or precious metals, formed with plaster or clay, or impressed onto a surface as applied ornament....
 and church bell
Church bell

A church bell is a bell which is rung in a church either to signify the hour or the time for worshippers to go to church, perhaps to attend a wedding, funeral, or other Service of worship....
s, is an alloy of tin
Tin

Tin is a chemical element with the symbol Sn and atomic number 50. Tin is obtained chiefly from the mineral cassiterite, where it occurs as an oxide, SnO2....
 and copper
Copper

Copper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity....
.

Unlike pure metals, most alloys do not have a single melting point
Melting point

The melting point of a solid is the temperature range at which it changes states of matter from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium....
. Instead, they have a melting range in which the material is a mixture of solid
Solid

A solid object is in the states of matter characterized by resistance to deformation and changes of volume. In other words, it has high values both of Young's modulus and of shear modulus; this contrasts e.g....
 and liquid
Liquid

Liquid is one of the principal states of matter. A liquid is a fluid that has the particles loose and can freely form a distinct surface at the boundaries of its bulk material....
 phases. The temperature at which melting begins is called the solidus
Solidus (chemistry)

In chemistry, materials science, and physics, the solidus is the locus of temperatures below which a given substance is completely solid . The solidus is applied, among else, to metal alloys, ceramics, and natural rocks and minerals....
 and the temperature when melting is complete is called the liquidus. However, for most alloys there is a particular proportion of constituents which give them a single melting point or (rarely) two. This is called the alloy's eutectic mixture.

Terminology

In practice, some alloys are used so predominantly with respect to their base metals that the name of the primary constituent is also used as the name of the alloy. For example, 14 karat gold
Gold

Gold is a chemical element with the symbol Au and atomic number 79. It is a highly sought-after precious metal, having been used as money, as a store of value, in jewelry, in sculpture, and for ornamentation since the beginning of recorded history....
 is an alloy of gold with other elements. Similarly, the silver
Silver

Silver is a chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal....
 used in jewelry and the aluminium
Aluminium

Aluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13....
 used as a structural building material are also alloys.

The term "alloy" is sometime used in everyday speech as a synonym for a particular alloy. For example, automobile wheels made of aluminium alloy
Aluminium alloy

Aluminium alloys are alloys of aluminium, often with copper, zinc, manganese, silicon, or magnesum. They are much lighter and more corrosion resistant than plain carbon steel, but not as corrosion resistant as pure aluminium....
 are commonly referred to as simply "alloy wheels". The usage is obviously indefinite, since steels and most other metals in practical use are also alloys.

See also


  • List of alloys
    List of alloys

    This is an incomplete list of named alloys grouped alphabetically by base metal. Within these headings they are in no particular order. Some of the main alloying elements are optionally listed after the alloy names....
  • Intermetallics
    Intermetallics

    Intermetallics or intermetallic compounds is a term that is used in a number of different ways. Most commonly it refers to solid state phases involving metals....
  • Heat treatment
    Heat treatment

    Heat treatment is a method used to alter the physical property, and sometimes chemical property, properties of a material. The most common application is metallurgy....
  • CALPHAD (method)


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