In metallurgy, an alloy (from Latin ligare 'bind, unite') is a
macroscopically homogeneous metallic material made up of at least two elements
(components), at least one of which is a metal and which together have the
metal-typical characteristic of the metal bond. [1] From a chemical point of
view, there are alloys that represent mixtures and intermetallic compounds with
a defined stoichiometric ratio of the metals involved. In general, alloys also
have a crystalline structure. However, there are also amorphous metallic
glasses.
Depending on the type of alloy formation, an alloy can be more homogeneous or
heterogeneous at the microscopic level. Alloys that form exclusively mixed
crystals or exclusively intermetallic compounds are homogeneous. All others,
which consist of several phases, are heterogeneous. [2]
The behavior of the elements in an alloy and their influence on their properties
generally depend on three factors: the type and number of alloy partners, their
mass fraction in the alloy and the temperature. These factors determine the
respective absorption capacity, i.e. the solubility of one element in the other
and whether the alloy partners form mixed crystals or mixtures of pure crystals
(also crystal mixtures) of the respective alloy components.
The verb verb is originally from the Latin ligare and means to bind together, to
connect or to unite. In the 17th century, the now slightly modified legare (with
the same meaning) was adopted into German.
Hastelloy G -30 / UNS N06035 HASTELLOY C-2000 (FOR SPRINGS) Monel 404 (UNS N 04404)
Nimonic90 Nickel 2.4683 (Alloy 188) Haynes˘ 214 Haynes 556 / UNS R30556 / 1.4883 Haynes 230® - 2.4733 - alloy 230 Monel 401 Metal piping
Hastelloy N / UNS N10003 Hastelloy B Alloy 926 / 6Mo alloy a 286 uns ss28286 1.498 alloy 28 UNS N08028, alloy 20 UNS N08020
INCOLOY® alloy 330 Incoloy 901® - 2.4975 - Alloy 901 Incoloy 028 1.4563 / Sanicro28 Inconel 693® - Alloy 693 Inconel 706 INCONEL® 740/740H Alloy
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Alloy 625 / Inconel 625 / N06625 / 2.4856
Alloy 601 / Inconel 601 / N06601 / 2.4851
Alloy 718 / Inconel 718 / N07718 / 2.4668
Alloy 690 / Inconel 690 / N06690 / 2.4642
Alloy 617 / Inconel 617 / N06617 / 2.4663
Alloy X-750 / Inconel X-750 / N07750 / 2.4669
Alloy 600 / Inconel 600 / N06600 / 2.4816
1.4876 / 1.4958: Corrosion-resistant and heat-resistant nickel-iron-chrome alloy
Alloy 800HT / Incoloy 800HT / N08811 / 1.4959
Alloy 825 / Incoloy 825 / N08825 / 2.4858
Alloy 800H / Incoloy 800H / N08810 / 1.4958
Alloy 20 / Incoloy 20 / N08020 / 2.4660
Alloy 925 / Incoloy 925 / UNS N09925
Alloy B-2 / Hastelloy B-2 / N10665 / 2.4617
Alloy C-276 / Hastelloy C-276 / N10276 / 2.4819
Alloy C-22 / Hastelloy C-22 / N06022 / 2.4602
Alloy B-3 / Hastelloy B-3 / UNS 10675 / 2.4600
Alloy C-4 / Hastelloy C-4 / N06455 / 2.4610
Alloy X / Hastelloy X / N06002 / 2.4665
Alloy 400 / Monel 400 / UNS N04400 / 2.4360
Alloy K-500 / Monel K-500 / N05500 / 2.4375
Alloy R-405 / Monel R-405 / N04405
properties
The alloy element can form a solid solution with the basic element (single-phase
alloy) or several phases can be formed. While the properties of single-phase
alloys are essentially determined by their chemical composition, those of
multi-phase alloys are also significantly influenced by the distribution of the
phases (structure). Base metal and alloy elements are also called components of
an alloy. They are listed in the list of alloying elements and their effects on
the respective base metals. Mixed crystals have a higher hardness and tensile
strength, but a lower melting temperature than the base metal. In the case of
metals, the electrical conductivity also drops. For the relatively soft, pure
metals, solid solution strengthening is one of four possible strength-increasing
processes to produce a hard material.
With the solidification of a cast alloy, the crystallization is not always
complete. Certain alloys can also improve their mechanical properties (fracture
resistance, hardness, elongation) as a casting - stored cold or warmed -
("tempered"). In the case of wrought alloys, the recrystallization that
solidifies the structure by cold aging or heat treatment is even a prerequisite
for the production of semi-finished products.
Examples of "natural alloys" are Elektrum, a gold-silver alloy, and Stibarsen,
an antimony-arsenic alloy.
In the case of ¡°artificially produced alloys¡±, a distinction is made between
those that were deliberately manufactured in order to change the material
properties (examples of hardness, corrosion resistance) of the ¡°base metals¡± in
the desired way, and those that are created unintentionally because foreign
substances (metallurgy) are already produced get into the alloy and can have
negative effects on the material properties. Examples of the latter include
bismuth and / or arsenic in Messingen, as well as bismuth in AlSi alloys, where
it greatly affects the microstructure.
history
Copper, tin and bronze
Bronze ax
Bronze ax
Copper is one of the first metals used by humans; it was probably discovered by
chance about 6000 to 10000 years ago in charcoal fires, which burned
particularly hot with air. It gave the Copper Stone Age its name. At a melting
point of 1083 ¡ã C, it can escape from copper veins in the rock in liquid form.
By heating copper-containing, oxidic ores, on the other hand, copper can only be
obtained with a reducing furnace, i.e. in the presence of charcoal. Tin was also
discovered early, about 5000 years ago. [4]
Bronze as an alloy of copper and tin (CuSn) has been around since about 3300 BC.
BC in Palestine. Bronze is harder and more cut than copper and gave an entire
cultural epoch its name, the Bronze Age. Commodities, tools, weapons and jewelry
were made of bronze. Many sculptures are still cast from bronze.
Brass
Brass figure
Brass figure
Brass is an alloy of copper and zinc (CuZn). Zinc, mostly in the form of zinc
carbonate "calamine" (smithsonite), has been around 3000 BC since the Bronze
Age. Used in Babylon and Assyria, in Palestine around 1400 to 1000 BC Chr. [6]
Brass quickly became an important coin metal in coinage, but because of its
beautiful, golden sheen, it was also often used to make jewelry and plastics.
Iron alloys
Iron sickle
Iron sickle
Iron alloys have been used in prehistoric times, but only from meteorites, which
often contain the iron-nickel (FeNi) alloy. Since meteorites were rarely found,
iron objects were valuable. The Sumerians called it "heavenly metal", the
ancient Egyptians "black copper from the sky". [7] Smelted iron (detected by the
absence of nickel) was found in Mesopotamia, Anatolia and Egypt and is about
3000 to 2000 BC. Chr. It was more valuable than gold and was used primarily for
ceremonial purposes. However, iron offered and offers many advantages, the most
important being the greater hardness compared to bronze and copper. Improvements
in extraction and processing caused people to start making weapons and then
tools such as plows from iron. The Bronze Age was thus replaced by the Iron Age.
Classification
Depending on the number of components in the alloy, one speaks of a two-,
three-, four- or multi-component alloy (binary, ternary, quaternary or polynary
alloy), whereby only those components are counted that determine the
characteristic properties. Since iron and steel are of particular importance in
technology, alloys are divided into iron and non-iron alloys. Further
classifications result from the type of alloy formation, since these do not only
result from the melting together of the components or also from the special
capabilities of alloys.
Natural alloys are created by exposure to heat and melting elements, for example
inside celestial bodies. Since these alloys were not controlled by humans, they
are not subject to their defined compositions and properties.
Iron alloys are divided into cast iron and steel. The distinction is based on
the carbon content. See main article iron-carbon diagram. Stainless steels are
particularly important: alloyed or unalloyed steels with a particular degree of
purity.
Non-ferrous alloys (non-ferrous alloys, e.g. bronze, brass, amalgams, white
gold, rose gold) are alloys based on non-ferrous metals.
Diffusion alloys are created by the diffusion of atoms into the crystal lattice
of the base metals. Because of the smallness of their atoms compared to the base
metal, the first elements in the periodic table in particular are able to
migrate into its crystal lattice. The best example of a diffusion alloy is the
carburizing of workpieces in order to be able to harden them (see tempering).
Heusler's alloys are very special ferromagnetic alloys that do not contain iron,
cobalt or nickel (example Cu2AlMn).
Shape memory alloys are metals that return to their original shape after being
deformed by exposure to heat.
Cast alloys are used for direct shaping.
Wrought alloys as a ¡°semi-finished product¡± are an intermediate product that is
intended for further rolling, pressing or drawing forming.
Pseudo-alloys are the workpieces created by sintering (pressing together
various, intimately mixed metal powders at high temperature). This process can
also be used to mix elements that would not dissolve in the molten state. Many
tungsten alloys are used e.g. B. manufactured in this way.
Alloy formula
In order to identify an alloy, the base metal is usually mentioned first,
followed by the key component (s) as an abbreviation for the metal with an
attached number, which represents the respective percentage (mass percentage).
An alloy CuZn37 (formerly called brass 63) consists of the copper base, to which
37% zinc has been added. With the iron-carbon alloy steel, there are deviations
from this system depending on the amount of the alloying elements. In any case,
the iron is never explicitly mentioned. Steel C37, for example, contains 0.37%
carbon and otherwise iron.
The specification of alloy proportions is partly due to the DIN 1310 composition
of mixed phases (gas mixture, solutions, mixed crystal); Basic terms regulated.
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