Alloy

Jump to: navigation, search

WikiDoc Resources for Alloy

Articles

Most recent articles on Alloy

Most cited articles on Alloy

Review articles on Alloy

Articles on Alloy in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Alloy

Images of Alloy

Photos of Alloy

Podcasts & MP3s on Alloy

Videos on Alloy

Evidence Based Medicine

Cochrane Collaboration on Alloy

Bandolier on Alloy

TRIP on Alloy

Clinical Trials

Ongoing Trials on Alloy at Clinical Trials.gov

Trial results on Alloy

Clinical Trials on Alloy at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Alloy

NICE Guidance on Alloy

NHS PRODIGY Guidance

FDA on Alloy

CDC on Alloy

Books

Books on Alloy

News

Alloy in the news

Be alerted to news on Alloy

News trends on Alloy

Commentary

Blogs on Alloy

Definitions

Definitions of Alloy

Patient Resources / Community

Patient resources on Alloy

Discussion groups on Alloy

Patient Handouts on Alloy

Directions to Hospitals Treating Alloy

Risk calculators and risk factors for Alloy

Healthcare Provider Resources

Symptoms of Alloy

Causes & Risk Factors for Alloy

Diagnostic studies for Alloy

Treatment of Alloy

Continuing Medical Education (CME)

CME Programs on Alloy

International

Alloy en Espanol

Alloy en Francais

Business

Alloy in the Marketplace

Patents on Alloy

Experimental / Informatics

List of terms related to Alloy


Overview

An alloy is a solid solution or homogeneous mixture of two or more elements, at least one of which is a metal, which itself has metallic properties. It usually has different properties from those of its component elements.

Alloying one metal with others often enhances its properties. For instance, steel is stronger than iron, its primary element. The physical properties, such as density, reactivity, Young's modulus, and electrical and thermal conductivity, of an alloy may not differ greatly from those of its elements, but engineering properties, such as tensile strength[1] and shear strength may be substantially different from those of the constituent materials. This is sometimes due to the sizes of the atoms 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.[2][3] Some alloys are made by melting and mixing two or more metals. Brass is an alloy made from copper and zinc. Bronze, used for statues, ornaments and church bells, is an alloy of tin and copper.

Unlike pure metals, most alloys do not have a single melting point. Instead, they have a melting range in which the material is a mixture of solid and liquid phases. The temperature at which melting begins is called the solidus 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.

Classification

Alloys can be classified by the number of their constituents. An alloy with two components is called a binary alloy; one with three is a ternary alloy, and so forth. Alloys can be further classified as either substitution alloys or interstitial alloys, depending on their method of formation. In substitution alloys, the atoms of the components are approximately the same size and the various atoms are simply substituted for one another in the crystal structure. An example of a (binary) substitution alloy is brass, made up of copper and zinc. Interstitial alloys occur when the atoms of one component are substantially smaller than the other and the smaller atoms fit into the spaces (interstices) between the larger atoms.

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 is an alloy of gold with other elements. Similarly, the silver used in jewelry and the aluminium 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 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

References

  1. Adelbert Phillo Mills, (1922) Materials of Construction: Their Manufacture and Properties, John Wiley & sons, inc, 489 pages, originally published by the University of Wisconsin, Madison
  2. C. Michael Hogan, (1969) Density of States of an Insulating Ferromagnetic Alloy Phys. Rev. 188, 870 - 874, [Issue 2 – December 1969
  3. X. Y. Zhang and H. Suhl (1985) Phys. Rev. A 32, 2530 - 2533 (1985) [Issue 4 – October 1985




Linked-in.jpg