Metallurgy is a domain of "materials science and engineering that studies the physical and chemical behavior of "metallic "elements, their "inter-metallic compounds, and their mixtures, which are called "alloys. Metallurgy is also the "technology of metals: the way in which science is applied to the production of metals, and the engineering of metal components for usage in products for consumers and manufacturers. The production of metals involves the processing of "ores to extract the metal they contain, and the mixture of metals, sometimes with other elements, to produce alloys. Metallurgy is distinguished from the "craft of "metalworking, although metalworking relies on metallurgy, as "medicine relies on medical science, for technical advancement.
Ferrous metallurgy involves processes and alloys based on "iron while non-ferrous metallurgy involves processes and alloys based on other metals. The production of ferrous metals accounts for 95 percent of world metal production.
The roots of metallurgy derive from Ancient Greek: μεταλλουργός, metallourgós, "worker in metal", from μέταλλον, métallon, "metal" + ἔργον, érgon, "work".
The word was originally an "alchemist's term for the extraction of metals from minerals, the ending -urgy signifying a process, especially manufacturing: it was discussed in this sense in the 1797 "Encyclopædia Britannica. In the late 19th century it was extended to the more general scientific study of metals, alloys, and related processes.
In English, the /meˈtælədʒi/ pronunciation is the more common one in the UK and Commonwealth. The /ˈmetələrdʒi/ pronunciation is the more common one in the USA, and is the first-listed variant in various American dictionaries (e.g., Merriam-Webster Collegiate, American Heritage).
The earliest recorded metal employed by humans appears to be "gold, which can be found free or "native". Small amounts of natural gold have been found in Spanish caves used during the late "Paleolithic period, c. 40,000 BC. "Silver, "copper, "tin and meteoric "iron can also be found in native form, allowing a limited amount of "metalworking in early cultures. Egyptian weapons made from "meteoric iron in about 3000 BC were highly prized as "daggers from heaven".
Certain metals, notably tin, "lead and (at a higher temperature) copper, can be recovered from their ores by simply heating the rocks in a fire or blast furnace, a process known as "smelting. The first evidence of this extractive metallurgy dates from the 5th and 6th millennia BC and was found in the archaeological sites of "Majdanpek, Yarmovac and "Plocnik, all three in "Serbia. To date, the earliest evidence of copper smelting is found at the "Belovode site, including a copper axe from 5500 BC belonging to the "Vinča culture. Other signs of early metals are found from the third millennium BC in places like "Palmela (Portugal), "Los Millares (Spain), and "Stonehenge (United Kingdom). However, the ultimate beginnings cannot be clearly ascertained and new discoveries are both continuous and ongoing.
These first metals were single ones or as found. About 3500 BC, it was discovered that by combining copper and tin, a superior metal could be made, an "alloy called "bronze, representing a major technological shift known as the "Bronze Age.
The extraction of "iron from its ore into a workable metal is much more difficult than for copper or tin. The process appears to have been invented by the "Hittites in about 1200 BC, beginning the "Iron Age. The secret of extracting and working iron was a key factor in the success of the "Philistines.
Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the "Middle East and "Near East, ancient "Iran, ancient "Egypt, ancient "Nubia, and "Anatolia ("Turkey), "Ancient Nok, "Carthage, the "Greeks and "Romans of ancient "Europe, medieval Europe, ancient and medieval "China, ancient and medieval "India, ancient and medieval "Japan, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China, such as the innovation of the "blast furnace, "cast iron, "hydraulic-powered "trip hammers, and double acting piston "bellows.
A 16th century book by "Georg Agricola called "De re metallica describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time. Agricola has been described as the "father of metallurgy".
"Extractive metallurgy is the practice of removing valuable metals from an "ore and refining the extracted raw metals into a purer form. In order to convert a metal "oxide or "sulphide to a purer metal, the ore must be "reduced physically, "chemically, or "electrolytically.
Extractive metallurgists are interested in three primary streams: feed, concentrate (valuable metal oxide/sulphide), and "tailings (waste). After mining, large pieces of the ore feed are broken through crushing and/or grinding in order to obtain particles small enough where each particle is either mostly valuable or mostly waste. Concentrating the particles of value in a form supporting separation enables the desired metal to be removed from waste products.
Mining may not be necessary if the ore body and physical environment are conducive to "leaching. Leaching dissolves minerals in an ore body and results in an enriched solution. The solution is collected and processed to extract valuable metals.
Ore bodies often contain more than one valuable metal. Tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal. That concentrate would then be processed to separate the valuable metals into individual constituents.
Common engineering "metals include "aluminium, "chromium, "copper, "iron, "magnesium, "nickel, "titanium and "zinc. These are most often used as alloys. Much effort has been placed on understanding the iron-carbon alloy system, which includes "steels and "cast irons. "Plain carbon steels (those that contain essentially only carbon as an alloying element) are used in low-cost, high-strength applications where weight and "corrosion are not a problem. Cast irons, including "ductile iron, are also part of the iron-carbon system.
Copper-nickel alloys (such as "Monel) are used in highly corrosive environments and for non-magnetic applications. Nickel-based "superalloys like "Inconel are used in high-temperature applications such as "gas turbines, "turbochargers, "pressure vessels, and "heat exchangers. For extremely high temperatures, "single crystal alloys are used to minimize "creep.
In "production engineering, metallurgy is concerned with the production of metallic components for use in consumer or "engineering products. This involves the production of alloys, the shaping, the heat treatment and the surface treatment of the product. The task of the metallurgist is to achieve balance between material properties such as cost, "weight, "strength, "toughness, "hardness, "corrosion, "fatigue resistance, and performance in "temperature extremes. To achieve this goal, the operating environment must be carefully considered. In a saltwater environment, ferrous metals and some aluminium alloys corrode quickly. Metals exposed to cold or "cryogenic conditions may endure a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from metal fatigue. Metals under constant "stress at elevated temperatures can "creep.
Metals are shaped by processes such as:
"Cold-working processes, in which the product’s shape is altered by rolling, fabrication or other processes while the product is cold, can increase the strength of the product by a process called "work hardening. Work hardening creates "microscopic defects in the metal, which resist further changes of shape.
Metals can be "heat-treated to alter the properties of strength, ductility, toughness, hardness and/or resistance to corrosion. Common heat treatment processes include "annealing, "precipitation strengthening, "quenching, and "tempering. The annealing process softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that when the metal is hit or stressed it dents or perhaps bends, rather than breaking; it is also easier to sand, grind, or cut annealed metal. Quenching is the process of cooling a high-carbon steel very quickly after heating, thus "freezing" the steel's molecules in the very hard martensite form, which makes the metal harder. There is a balance between hardness and toughness in any steel; the harder the steel, the less tough or impact-resistant it is, and the more impact-resistant it is, the less hard it is. Tempering relieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking.
Often, mechanical and thermal treatments are combined in what are known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high-alloy special steels, "superalloys and titanium alloys.
"Electroplating is a chemical surface-treatment technique. It involves bonding a thin layer of another metal such as "gold, "silver, "chromium or "zinc to the surface of the product. It is used to reduce corrosion as well as to improve the product's aesthetic appearance.
Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings.
Metallurgists study the microscopic and macroscopic properties using "metallography, a technique invented by "Henry Clifton Sorby. In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal. The sample is then examined in an optical or "electron microscope, and the image contrast provides details on the composition, mechanical properties, and processing history.
"Crystallography, often using "diffraction of "x-rays or "electrons, is another valuable tool available to the modern metallurgist. Crystallography allows identification of unknown materials and reveals the crystal structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been subjected.
EMC, the European Metallurgical Conference has developed to the most important networking business event dedicated to the non-ferrous metals industry in Europe. From the start of the conference sequence in 2001 at Friedrichshafen it was host of the most relevant metallurgists from all countries of the world. The European Metallurgical Conference is organized by GDMB Society of Metallurgists and Miners.
|"Wikisource has the text of the 1879 "American Cyclopædia article Metallurgy.|