Metallurgy

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 used to separate metals from their ore. 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. The science of metallurgy is subdivided into chemical metallurgy and physical metallurgy.

Metallurgy is subdivided into ferrous metallurgy (also known as black metallurgy) and non-ferrous metallurgy (also known as colored metallurgy). 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.[1]

Processing gold
Smelting, a basic step in obtaining usable quantities of most metals.
Pouring gold
Casting; pouring molten gold into an ingot.

Etymology and pronunciation

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.[2] In the late 19th century it was extended to the more general scientific study of metals, alloys, and related processes.

In English, the /mɛˈtælərdʒi/ pronunciation is the more common one in the UK and Commonwealth. The /ˈmɛtəlɜːrdʒi/ 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).

History

GoldThebes750
Gold headband from Thebes 750–700 BC

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.[3] Silver, copper, tin and meteoric iron can also be found in native form, allowing a limited amount of metalworking in early cultures.[4] Egyptian weapons made from meteoric iron in about 3000 BC were highly prized as "daggers from heaven".[5]

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, dating from the 5th and 6th millennia BC,[6] has been found at archaeological sites in Majdanpek, Yarmovac, and Plocnik, in present-day Serbia. To date, the earliest evidence of copper smelting is found at the Belovode site near Plocnik.[7] This site produced a copper axe from 5500 BC, belonging to the Vinča culture.[8]

The earliest use of lead is documented from the late neolithic settlement of Yarim Tepe in Iraq,

"The earliest lead (Pb) finds in the ancient Near East are a 6th millennium BC bangle from Yarim Tepe in northern Iraq and a slightly later conical lead piece from Halaf period Arpachiyah, near Mosul.[9] As native lead is extremely rare, such artifacts raise the possibility that lead smelting may have begun even before copper smelting."[10][11]

Copper smelting is also documented at this site at about the same time period (soon after 6000 BC), although the use of lead seems to precede copper smelting. Early metallurgy is also documented at the nearby site of Tell Maghzaliyah, which seems to be dated even earlier, and completely lacks pottery.

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.

Metal production in Ancient Middle East
Mining areas of the ancient Middle East. Boxes colors: arsenic is in brown, copper in red, tin in grey, iron in reddish brown, gold in yellow, silver in white and lead in black. Yellow area stands for arsenic bronze, while grey area stands for tin bronze.

In the Near East, about 3500 BC, it was discovered that by combining copper and tin, a superior metal could be made, an alloy called bronze. This represented 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.[5][12]

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.[13][14]

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".[15]

Extraction

Yuan Dynasty - waterwheels and smelting
Furnace bellows operated by waterwheels, Yuan Dynasty, China.
Žiar nad Hronom2
Aluminium plant in Žiar nad Hronom (Central Slovakia)

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.

Alloys

Bois-du-Luc - Fondeur d'art 2
Casting bronze

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.

Stainless steel or galvanized steel is used where resistance to corrosion is important. Aluminium alloys and magnesium alloys are used for applications where strength and lightness are required.

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.

Production

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. Determining the hardness of the metal using the Rockwell, Vickers, and Brinell hardness scales is a commonly used practice that helps better understand the metal’s elasticity and plasticity for different applications and production processes.[16] 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.

Metalworking processes

Metals are shaped by processes such as:

  • Casting – molten metal is poured into a shaped mold.
  • Forging – a red-hot billet is hammered into shape.
  • Rolling – a billet is passed through successively narrower rollers to create a sheet.
  • Laser cladding – metallic powder is blown through a movable laser beam (e.g. mounted on a NC 5-axis machine). The resulting melted metal reaches a substrate to form a melt pool. By moving the laser head, it is possible to stack the tracks and build up a three-dimensional piece.
  • Extrusion – a hot and malleable metal is forced under pressure through a die, which shapes it before it cools.
  • Sintering – a powdered metal is heated in a non-oxidizing environment after being compressed into a die.
  • Machininglathes, milling machines, and drills cut the cold metal to shape.
  • Fabrication – sheets of metal are cut with guillotines or gas cutters and bent and welded into structural shape.
  • 3D printing – Sintering or melting amorphous powder metal in a 3D space to make any object to shape.

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.

Various forms of casting exist in industry and academia. These include sand casting, investment casting (also called the lost wax process), die casting, and continuous castings. Each of these forms has advantages for certain metals and applications considering factors like magnetism and corrosion.[17]

Heat treatment

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.[18] 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.

Plating

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. This is done by selecting the coating material electrolyte solution which is the material that is going to coat the workpiece (gold, silver,...zinc). There needs to be two electrodes of different materials: one the same material as the coating material and one that is receiving the coating material. then the two electrodes are electrically charged and the coating material is stuck to the workpiece. It is used to reduce corrosion as well as to improve the product's aesthetic appearance. It is also used to make inexpensive metals look like the more expensive ones (gold, silver).[19]

Shot peening

Shot peening is a cold working process used to finish metal parts. In the process of shot peening, small round shot is blasted against the surface of the part to be finished. This process is used to prolong the product life of the part, prevent stress corrosion failures, and also prevent fatigue. The shot leaves small dimples on the surface like a peen hammer does, which cause compression stress under the dimple. As the shot media strikes the material over and over, it forms many overlapping dimples throughout the piece being treated. The compression stress in the surface of the material strengthens the part and makes it more resistant to fatigue failure, stress failures, corrosion failure, and cracking.[20]

Thermal spraying

Thermal spraying techniques are another popular finishing option, and often have better high temperature properties than electroplated coatings.Thermal spraying, also known as a spray welding process,[21] is an industrial coating process that consists of a heat source (flame or other) and a coating material that can be in a powder or wire form which is melted then sprayed on the surface of the material being treated at a high velocity. The spray treating process is known by many different names such as hvof, plasma spray, flame spray, arc spray, and metalizing.

AlubronzeCuAl20v500
Metallography allows the metallurgist to study the microstructure of metals.

Microstructure

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.

See also

References

  1. ^ "Металлургия". in The Great Soviet Encyclopedia. 1979.
  2. ^ Oxford English Dictionary, accessed 29 January 2011
  3. ^ "History of Gold". Gold Digest. Retrieved 4 February 2007.
  4. ^ E. Photos, E. (2010). "The Question of Meteoritic versus Smelted Nickel-Rich Iron: Archaeological Evidence and Experimental Results" (PDF). World Archaeology. 20 (3): 403–421. doi:10.1080/00438243.1989.9980081. JSTOR 124562.
  5. ^ a b W. Keller (1963) The Bible as History. p. 156. ISBN 0-340-00312-X
  6. ^ H.I. Haiko, V.S. Biletskyi. First metals discovery and development the sacral component phenomenon. // Theoretical and Practical Solutions of Mineral Resources Mining // A Balkema Book, London, 2015, р. 227-233..
  7. ^ Radivojević, Miljana; Rehren, Thilo; Pernicka, Ernst; Šljivar, Dušan; Brauns, Michael; Borić, Dušan (2010). "On the origins of extractive metallurgy: New evidence from Europe". Journal of Archaeological Science. 37 (11): 2775. doi:10.1016/j.jas.2010.06.012.
  8. ^ Neolithic Vinca was a metallurgical culture Stonepages from news sources November 2007
  9. ^ Moorey 1994: 294
  10. ^ Craddock 1995: 125
  11. ^ Potts, Daniel T., ed. (15 August 2012). "Northern Mesopotamia". A Companion to the Archaeology of the Ancient Near East. 1. John Wiley & Sons, 2012. p. 302. ISBN 978-1-4443-6077-6.
  12. ^ B. W. Anderson (1975) The Living World of the Old Testament, p. 154, ISBN 0-582-48598-3
  13. ^ R. F. Tylecote (1992) A History of Metallurgy ISBN 0-901462-88-8
  14. ^ Robert K.G. Temple (2007). The Genius of China: 3,000 Years of Science, Discovery, and Invention (3rd edition). London: André Deutsch. pp. 44–56. ISBN 978-0-233-00202-6.
  15. ^ Karl Alfred von Zittel (1901). History of Geology and Palaeontology. p. 15. doi:10.5962/bhl.title.33301.
  16. ^ "Metal Hardness Tests: Difference Between Rockwell, Brinell, and Vickers". ESI Engineering Specialties Inc. 14 June 2017. Retrieved 13 December 2017.
  17. ^ "Casting Process, Types of Casting Process, Casting Process Tips, Selecting Casting Process, Casting Process Helps". www.themetalcasting.com. Retrieved 13 December 2017.
  18. ^ Arthur Reardon (2011), Metallurgy for the Non-Metallurgist (2nd edition), ASM International, ISBN 978-1-61503-821-3
  19. ^ "How electroplating works". Explain that Stuff.
  20. ^ "What is Shot Peening – How Does Shot Peening Work". www.engineeredabrasives.com.
  21. ^ "Thermal Spray, Plasma Spray, HVOF, Flame Spray, Metalizing & Thermal Spray Coating". www.precisioncoatings.com. Saint Paul, MN. Retrieved 13 December 2017.

External links

AGH University of Science and Technology

AGH University of Science and Technology (Polish Akademia Górniczo-Hutnicza im. Stanisława Staszica) is a technical university in Poland, located in Kraków. The university was established in 1919, and was formerly known as the University of Mining and Metallurgy. It has 15 faculties and one school, which will become a faculty in the near future.

Annealing (metallurgy)

Annealing, in metallurgy and materials science, is a heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and reduce its hardness, making it more workable. It involves heating a material above its recrystallization temperature, maintaining a suitable temperature for a suitable amount of time, and then cooling.

In annealing, atoms migrate in the crystal lattice and the number of dislocations decreases, leading to a change in ductility and hardness. As the material cools it recrystallizes. For many alloys, including carbon steel, the crystal grain size and phase composition, which ultimately determine the material properties, are dependent on the heating, and cooling rate. Hot working or cold working after the annealing process alter the metal structure, so further heat treatments may be used to achieve the properties required. With knowledge of the composition and phase diagram, heat treatment can be used to adjust between harder and more brittle, to softer and more ductile.

In the cases of copper, steel, silver, and brass, this process is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. Copper, silver and brass can be cooled slowly in air, or quickly by quenching in water, unlike ferrous metals, such as steel, which must be cooled slowly to anneal. In this fashion, the metal is softened and prepared for further work—such as shaping, stamping, or forming.

Blast furnace

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.In a blast furnace, fuel (coke), ores, and flux (limestone) are continuously supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place throughout the furnace as the material falls downward. The end products are usually molten metal and slag phases tapped from the bottom, and waste gases (flue gas) exiting from the top of the furnace. The downward flow of the ore and flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process.In contrast, air furnaces (such as reverberatory furnaces) are naturally aspirated, usually by the convection of hot gases in a chimney flue. According to this broad definition, bloomeries for iron, blowing houses for tin, and smelt mills for lead would be classified as blast furnaces. However, the term has usually been limited to those used for smelting iron ore to produce pig iron, an intermediate material used in the production of commercial iron and steel, and the shaft furnaces used in combination with sinter plants in base metals smelting.

Bronze

Bronze is a 80+% copper alloy and 90+% copper&tin alloy (commonly 12–12.5% tin) with often the addition of other metals, such as aluminium, manganese, nickel or zinc, and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon. These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as stiffness, ductility, or machinability.

The archeological period in which bronze was the hardest metal in widespread use is known as the Bronze Age. The beginning of the Bronze Age in India and western Eurasia is conventionally dated to the mid-4th millennium BC, and to the early 2nd millennium BC in China; everywhere it gradually spread across regions. The Bronze Age was followed by the Iron Age starting from about 1300 BC and reaching most of Eurasia by about 500 BC, although bronze continued to be much more widely used than it is in modern times.

Because historical pieces were often made of brasses (copper and zinc) and bronzes with different compositions, modern museum and scholarly descriptions of older objects increasingly use the more inclusive term "copper alloy" instead.

Department of Materials, University of Oxford

The Department of Materials at the University of Oxford, England was founded in the 1950s as the Department of Metallurgy, by William Hume-Rothery, who was a reader in Oxford's Department of Inorganic Chemistry. It is part of the university's Mathematical, Physical and Life Sciences Division

Around 250 people work in the Department of Materials full-time, including professors, lecturers, independent fellows, researchers and support staff. There are around 30 academic staff positions of which four are Chairs.

The Isaac Wolfson Chair in Metallurgy was set up in the late 1950s and remains one of the most important professorships in British materials science. Professor Sir Peter Hirsch formerly held the chair. The current holder of the chair is Peter Bruce FRS. Other Chairs in the Department include the Vesuvius Chair of Materials held by Patrick Grant FREng, Professor in the Physical Examination of Materials formerly held by David Cockayne FRS and the James Martin Chair in Energy Materials held by James Marrow.

Oxford Materials is a research intensive department, achieving 6* status in a research assessment exercise. World leading research is done in the broad fields of structural and nuclear materials, device materials, polymers and biomaterials, nanomaterials, processing and manufacturing, characterization, and computational materials modelling.

The Department offers undergraduate degrees in Materials Science and Materials, Economics and Management, having around 100 undergraduates, and around 75 postgraduate students, particularly DPhil students pursuing advanced research.In addition to its own buildings, the Department shares 7 buildings with the Department of Engineering Science on a triangular plot with Banbury Road to the west and Parks Road to the east. In addition, the Department has extensive, large-scale facilities at Begbroke Science Park, north of the city.

Department of Materials Science and Metallurgy, University of Cambridge

The Department of Materials Science and Metallurgy (DMSM) is a large research and teaching division of the University of Cambridge. Since 2013 it has been located in West Cambridge., having previously occupied several buildings on the New Museums Site in the centre of Cambridge.

Extractive metallurgy

Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications.The field of ferrous and non-ferrous extractive metallurgy have specialties that are generically grouped into the categories of mineral processing, hydrometallurgy, pyrometallurgy, and electrometallurgy based on the process adopted to extract the metal. Several processes are used for extraction of same metal depending on occurrence and chemical requirements.

Ferrous metallurgy

Ferrous metallurgy is the metallurgy of iron and its alloys. It began far back in prehistory. The earliest surviving iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the 2nd millennium BC iron was being produced from iron ores from Sub-Saharan Africa to China. The use of wrought iron (worked iron) was known by the 1st millennium BC, and its spread marked the Iron Age. During the medieval period, means were found in Europe of producing wrought iron from cast iron (in this context known as pig iron) using finery forges. For all these processes, charcoal was required as fuel.

Steel (with a carbon content between pig iron and wrought iron) was first produced in antiquity as an alloy. Its process of production, Wootz steel, was exported before the 4th century BC from India to ancient China, Africa, the Middle East and Europe. Archaeological evidence of cast iron appears in 5th-century BC China. New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century. During the Industrial Revolution, new methods of producing bar iron by substituting coke for charcoal were devised and these were later applied to produce steel, creating a new era of greatly increased use of iron and steel that some contemporaries described as a new Iron Age. In the late 1850s, Henry Bessemer invented a new steelmaking process, that involved blowing air through molten pig iron to burn off carbon, and so to produce mild steel. This and other 19th-century and later steel making processes have displaced wrought iron. Today, wrought iron is no longer produced on a commercial scale, having been displaced by the functionally equivalent mild or low carbon steel.The largest and most modern underground iron ore mine in the world is located in Kiruna, Norrbotten County, Lapland. The mine which is owned by Luossavaara-Kiirunavaara AB, a large Swedish mining company, has an annual production capacity of over 26 million tonnes of iron ore.

History of metallurgy in the Indian subcontinent

The history of metallurgy in the Indian subcontinent began prior to the 3rd millennium BCE and continued well into the British Raj. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term Ayas (metal). The Indian cultural and commercial contacts with the Near East and the Greco-Roman world enabled an exchange of metallurgic sciences. With the advent of the Mughals, India's Mughal Empire (established: April 21, 1526—ended: September 21, 1857) further improved the established tradition of metallurgy and metal working in India.The imperial policies of the British Raj led to stagnation of metallurgy in India as the British regulated mining and metallurgy—used in India previously by its rulers to build armies and resist England during various wars.

Iron Age

The Iron Age is the final epoch of the three-age division of the prehistory and protohistory of humankind. It was preceded by the Stone Age (Paleolithic, Mesolithic, Neolithic, and Chalcolithic) and the Bronze Age. The concept has been mostly applied to Europe and the Ancient Near East, and, by analogy, also to other parts of the Old World.

The duration of the Iron Age varies depending on the region under consideration. It is defined by archaeological convention, and the mere presence of some cast or wrought iron is not sufficient to represent an Iron Age culture; rather, the "Iron Age" begins locally when the production of iron or steel has been brought to the point where iron tools and weapons superior to their bronze equivalents become widespread. For example, Tutankhamun's meteoric iron dagger comes from the Bronze Age. In the Ancient Near East, this transition takes place in the wake of the so-called Bronze Age collapse, in the 12th century BC. The technology soon spread throughout the Mediterranean Basin region and to South Asia. Its further spread to Central Asia, Eastern Europe, and Central Europe is somewhat delayed, and Northern Europe is reached still later, by about 500 BC.

The Iron Age is taken to end, also by convention, with the beginning of the historiographical record.

This usually does not represent a clear break in the archaeological record; for the Ancient Near East the establishment of the Achaemenid Empire c. 550 BC (considered historical by virtue of the record by Herodotus) is usually taken as a cut-off date, and in Central and Western Europe the Roman conquests of the 1st century BC serve as marking for the end of the Iron Age. The Germanic Iron Age of Scandinavia is taken to end c. AD 800, with the beginning of the Viking Age.

In South Asia, the Iron Age is taken to begin with the ironworking Painted Gray Ware culture and to end with the reign of Ashoka (3rd century BC). The use of the term "Iron Age" in the archaeology of South, East and Southeast Asia is more recent, and less common, than for western Eurasia; at least in China prehistory had ended before iron-working arrived, so the term is infrequently used. The Sahel (Sudan region) and Sub-Saharan Africa are outside of the three-age system, there being no Bronze Age, but the term "Iron Age" is sometimes used in reference to early cultures practicing ironworking such as the Nok culture of Nigeria.

Materials science

The interdisciplinary field of materials science, also commonly termed materials science and engineering is the design and discovery of new materials, particularly solids. The intellectual origins of materials science stem from the Enlightenment, when researchers began to use analytical thinking from chemistry, physics, and engineering to understand ancient, phenomenological observations in metallurgy and mineralogy. Materials science still incorporates elements of physics, chemistry, and engineering. As such, the field was long considered by academic institutions as a sub-field of these related fields. Beginning in the 1940s, materials science began to be more widely recognized as a specific and distinct field of science and engineering, and major technical universities around the world created dedicated schools of the study, within either the Science or Engineering schools, hence the naming.

Materials science is a syncretic discipline hybridizing metallurgy, ceramics, solid-state physics, and chemistry. It is the first example of a new academic discipline emerging by fusion rather than fission.Many of the most pressing scientific problems humans currently face are due to the limits of the materials that are available and how they are used. Thus, breakthroughs in materials science are likely to affect the future of technology significantly.Materials scientists emphasize understanding how the history of a material (its processing) influences its structure, and thus the material's properties and performance. The understanding of processing-structure-properties relationships is called the § materials paradigm. This paradigm is used to advance understanding in a variety of research areas, including nanotechnology, biomaterials, and metallurgy. Materials science is also an important part of forensic engineering and failure analysis – investigating materials, products, structures or components which fail or do not function as intended, causing personal injury or damage to property. Such investigations are key to understanding, for example, the causes of various aviation accidents and incidents.

Metallurgy in pre-Columbian America

Metallurgy in pre-Columbian America is the extraction, purification and alloying of metals and metal crafting by Indigenous peoples of the Americas prior to European contact in the late 15th century. Indigenous Americans have been using native metals from ancient times, with recent finds of gold artifacts in the Andean region dated to 2155–1936 BCE, and North American copper finds dated to approximately 5000 BCE. The metal would have been found in nature without need for smelting techniques and shaped into the desired form using heat and cold hammering techniques without chemically altering it by alloying it. To date "no one has found evidence that points to the use of melting, smelting and casting in prehistoric eastern North America." In South America the case is quite different. Indigenous South Americans had full metallurgy with smelting and various metals being purposely alloyed. Metallurgy in Mesoamerica and Western Mexico may have developed following contact with South America through Ecuadorian marine traders.

Non-ferrous metal

In metallurgy, a non-ferrous metal is a metal, including alloys, that does not contain iron (ferrite) in appreciable amounts.

Generally more costly than ferrous metals, non-ferrous metals are used because of desirable properties such as low weight (e.g. aluminium), higher conductivity (e.g. copper), non-magnetic property or resistance to corrosion (e.g. zinc). Some non-ferrous materials are also used in the iron and steel industries. For example, bauxite is used as flux for blast furnaces, while others such as wolframite, pyrolusite and chromite are used in making ferrous alloys.Important non-ferrous metals include aluminium, copper, lead, nickel, tin, titanium and zinc, and alloys such as brass. Precious metals such as gold, silver and platinum and exotic or rare metals such as cobalt, mercury, tungsten, beryllium, bismuth, cerium, cadmium, niobium, indium, gallium, germanium, lithium, selenium, tantalum, tellurium, vanadium, and zirconium are also non-ferrous. They are usually obtained through minerals such as sulfides, carbonates, and silicates. Non-ferrous metals are usually refined through electrolysis.

Powder metallurgy

Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can avoid, or greatly reduce, the need to use metal removal processes, thereby drastically reducing yield losses in manufacture and often resulting in lower costs.

Powder metallurgy is also used to make unique materials impossible to get from melting or forming in other ways. A very important product of this type is tungsten carbide (WC). WC is used to cut and form other metals and is made from WC particles bonded with cobalt. It is very widely used in industry for tools of many types and globally ~50,000t/yr is made by PM. Other products include sintered filters, porous oil-impregnated bearings, electrical contacts and diamond tools.

Since the advent of industrial production–scale metal powder–based additive manufacturing (AM) in the 2010s, selective laser sintering and other metal AM processes are a new category of commercially important powder metallurgy applications.

Puddling (metallurgy)

Puddling was one step in one of the most important processes of making the first appreciable volumes of high-grade bar iron (malleable wrought iron) during the Industrial Revolution. In the original puddling technique, molten iron in a reverberatory furnace was stirred with rods, which were consumed in the process. It was one of the first processes for making bar iron without charcoal in Europe, although much earlier coal-based processes had existed in China. Eventually, the furnace would be used to make small quantities of specialty steels.

Though it was not the first process to produce bar iron without charcoal, puddling was by far the most successful, and replaced the earlier potting and stamping processes, as well as the much older charcoal finery and bloomery processes. This enabled a great expansion of iron production to take place in Great Britain, and shortly afterwards, in North America. That expansion constitutes the beginnings of the Industrial Revolution so far as the iron industry is concerned. Most 19th century applications of wrought iron, including the Eiffel Tower, bridges, and the original framework of the Statue of Liberty, used puddled iron.

Later the furnaces were also used to produce a good-quality carbon steel. This was a highly skilled art, and both high-carbon and low-carbon steels were successfully produced on a small scale, particularly for the gateway technology of tool steel as well as high quality swords, knives and other weapons.

Roman metallurgy

Metals and metal working had been known to the people of modern Italy since the Bronze Age. By 53 BCE, Rome had already expanded to control an immense expanse of the Mediterranean. This included nine provinces radiating from Italy to its islands, Spain, Macedonia, Africa, Asia Minor, Syria and Greece, and by the end of the Emperor Trajan's reign, the Roman Empire had grown further to encompass parts of Britain, Egypt, all of modern Germany west of the Rhine, Dacia, Noricum, Judea, Armenia, Illyria and Thrace (Shepard 1993). As the empire grew, so did its need for metals.

Central Italy itself was not rich in metal ores, leading to necessary trade networks in order to meet the demand for metal from the Republic. Early Italians had some access to metals in the northern regions of the peninsula in Tuscany and Cisalpine Gaul, as well as the islands Elba and Sardinia. With the conquest of Etruria in 275 BC and the subsequent acquisitions due to the Punic Wars, Rome had the ability to stretch further into Transalpine Gaul and Iberia, both areas rich in minerals. At the height of the Roman Empire, Rome exploited mineral resources from Tingitana in north western Africa to Egypt, Arabia to North Armenia, Galatia to Germania, and Britannia to Iberia, encompassing all of the Mediterranean coast. Britannia, Iberia, Dacia, and Noricum were of special significance, as they were very rich in deposits and became major sites of resource exploitation (Shepard, 1993).

There is evidence that after the middle years of the Empire there was a sudden and steep decline in mineral extraction. This was mirrored in other trades and industries.

One of the most important Roman sources of information is the Naturalis Historia of Pliny the Elder who died in the eruption of Mount Vesuvius in 79 AD. Several books (XXXIII–XXXVII) of his encyclopedia cover metals and metal ores, their occurrence, importance and development.

Solid-state physics

Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from their atomic-scale properties. Thus, solid-state physics forms a theoretical basis of materials science. It also has direct applications, for example in the technology of transistors and semiconductors.

University of Texas at El Paso

The University of Texas at El Paso (UTEP) is a public research university in El Paso, Texas. It is a member of the University of Texas System. UTEP is the second-largest university in the United States to have a majority Mexican American student population (about 80%) after the University of Texas Rio Grande Valley. The university's School of Engineering is the nation's top producer of Hispanic engineers with M.S. and Ph.D. degrees.On January 9, 2019, it was announced that UTEP is now classified as an "R1: Research University (Highest research activity)" in the Carnegie Classification of Institutions of Higher Education. This designation is reserved for doctoral universities with the highest levels of research activity.

UTEP is home to the Sun Bowl stadium, which hosts the annual college football competition the Sun Bowl every winter.

The campus is one of the few places in the world outside of Bhutan or Tibet to have buildings created with the Dzong architectural style. It sits on hillsides overlooking the Rio Grande river, with Ciudad Juárez in view across the Mexico–United States border.

University of Zagreb

The University of Zagreb (Croatian: Sveučilište u Zagrebu, pronounced [sʋeǔt͡ʃiliːʃte u zǎːgrebu]; Latin: Universitas Studiorum Zagrabiensis) is the largest Croatian university and the oldest continuously operating university in the area covering Central Europe south of Vienna and all of Southeastern Europe.The history of the University began on September 23, 1669, when the Holy Roman Emperor Leopold I issued a decree granting the establishment of the Jesuit Academy of the Royal Free City of Zagreb. The decree was accepted at the Council of the Croatian Kingdom on November 3, 1671. The Academy was run by the Jesuits for more than a century until the order was dissolved by Pope Clement XIV in 1773. In 1776, Empress Maria Theresa issued a decree founding the Royal Academy of Science which succeeded the previous Jesuit Academy. Bishop Josip Juraj Strossmayer proposed the founding of a University to the Croatian Parliament in 1861. Emperor Franz Joseph signed the decree on the establishment of the University of Zagreb in 1869. The Act of Founding was passed by the Parliament in 1874, and was ratified by the Emperor on January 5, 1874. On October 19, 1874, the Royal University of Franz Joseph I was officially opened.

The University is composed of 29 faculties, 3 art academies and 1 university center with more than 70.000 students. The University is as of 2018 at the 463rd place out of 1000 on the list of Universities of the world made by the Center for University World Rankings.

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