Introduction
This Introduction is talking about the aluminium alloys by dispersion strengthening and precipitation hardening. Firstly, is the dispersion strengthening to introduce. The dispersion strengthening is the some of metal alloys of hardness may be raise by some very small and even dispersed particles in the origin phase matrix. Whether inside the powder compaction contain of some insoluble particles ,this call dispersion strengthening. The other phases of the particle are normally the most strong strengthening agent .This phase of particle is practically very high strength in the engineering materials. This phase of particle can controls properties of the alloy by the shape, size and amount. This phase is call the second phase.
At the end of the 19th century, cast iron was the important commercial alloy not already known to the western technology at the time of Romans. When age hardening of the aluminium was discovered by Wilm, during the years 1903-1911, it quickly became an important commercial alloy under the trade name Duralumin.
The precipitation hardening is use the heat treatment process, the heat treatment process of precipitation hardening of the hardness that precipitated nanoscale and microscale intermetallic to avoid reproduce increment of the lattice defects, such as the dislocations is occur. These precipitates is a greatly strengthen of the metal matrix. The metal alloys of hardness may be enhance by a formation of very small and even dispersed particles of a second phase in the origin phase matrix, this will fulfil by a possible heat treatment. As with tempering the between loss of dutility and toughness and resulting increase in strength a balance will be struck when the precipitation hardening. Otherwi...
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...n of anti phase boundaries.
Figure 8: show the anti phase boundaries.
Reference
1) N.kalu. 2003. What is precipitation hardening?
Viewed on 24 February 2014.
Available from: http://www.wisegeek.com/what-is-precipitation-hardening.htm
2) J.s.benjamin.1977. Dispersion strengthened aluminium made by mechanical alloying. Viewed on 24 February 2014. Available from: http://link.springer.com/article/10.1007%2FBF02643845#page-1
3) Dispersion strengthening. Viewed on 24 February 2014. Available from: http://www.slideshare.net/sanjeeviitbhu/dispersion-strengthening
4) Dispersion strengthens and precipitation hardening. Viewed on 25 February 2014. Available from: http://academic.uprm.edu/pcaceres/Courses/MatEng/MSE6-2
5) Dispersion strengthening. Viewed on 25 February 2014. Available from: http://web.sunybroome.edu/~biegen_j/matsci/lectures/chap11/DIS11.HTM
We use metals to construct all kinds of structures, from bridges to skyscrapers to elevators. The strength as well as durability of materials that are crafted out of metal make the materials ideal not only for construction but also for many other applications.
was the period marked by the use of Iron. Iron Age follows immediately after the Bronze Age. The use of iron made the military stronger and powerful. Thus, it demonstrates KC 1.3: II.D because they developed weapons and tools that transformed warfare but also changes in agricultural practices, religious beliefs and artistic styles in society. It illustrates development and interaction of cultures, science & technology, writings, and languages that were used in the Iron Age, preceded by the Bronze Age. The Bronze has developed earliest alphabets such as the Cuneiform and the Hieroglyphic script, followed by the Iron Age, the Vedas were written. Iron Age has begun near East, ancient Iran, ancient India, and ancient Greece.
The term “zinc” was not in use until the 16th century, at the earliest. The ancient Greeks called it “pseudargyras,” meaning “false silver,” and made very little use of it (Mathewson 1). The unassuming bluish-gray mineral was given a warmer welcome by the Romans, who were already using it to make brass by “about the time of Augustus, 20BC to 14AD”; the Romans used, not purified zinc, but the mineral calamine (“zincky wall accretions” from caves) and fused them in a crucible with bits of copper to make their brass (Mathewson 1). Around the world, zinc was being exploited by the Chinese civilization as well, although documentation of Asian use of zinc does not come until the 7th century of AD, from Kazwiui, the “Pliny of the Orient.” Kazwiui, “who died in 630AD, stated that the Chinese knew how to render the metal malleable and used it to make small coins and mirrors” (Mathewson 2). The discovery and use of zinc, then, was widespread in ancient times and through the Middle Ages. However, it seems that it had not yet been used for anything much more practical than a mirror, a fact that would very quickly change in the 18th and 19th centuries as higher-grade zinc became available and new applications presented themselves.
A wide variety of coating alloys and wrought alloys can be prepared that give the metal greater strength, castability, or resistance to corrosion or high temperatures. Some new alloys can be used as armor plate for tanks, personnel carriers, and other military vehicles.
The Norse “Metallic Ages,” so called because they date the time periods when the Norse people are recorded to have been working with metals such as copper, bronze, and iron. This Age also includes the Migration Period (the Age of Heroes), because it happened during the time of the Germanic Iron Age when there were great southerly migrations of the Nordic people.
Arsenic has been one of the elements most mentioned during the middle and even modern age. It was formerly known by Chinese, Romans, Greeks and even earlier, by the Babylonians. The Greeks used the arsenic oxide (III) as a depilatory, and 4,000 years before the Christian era, arsenic was involved in the development of early bronzes. However, the arsenic was released in early civilizations through compounds or substances containing the element, which by its color and appearance would favor the conversion of base metals into gold. It was also used by the alchemists in the method of making the pill of immortality. In the philosophy of alchemy, arsenic represents the masculine principle. The masculinity of arsenic was different, because it combined with an element that was considered as masculine such as sulfur, forming orpiment and realgar.
The earliest evidence of welding dates back to the Bronze Age. The earliest examples of welding that have been found to date are welded gold boxes belonging to civilizations that thrived during the bronze age. There is evidence supporting the fact that even the Egyptians developed a form of welding. Several of their iron tools were made by welding. During the Middle Ages, a set of blacksmiths came to the forefront, crafting tools, weapons and other necessities. Blacksmiths of the Middle Ages welded various types of iron tools by hammering. The welding methods remained more or less unchanged until the 19th century. Where welding methods began to resemble conventional welding processes through innovations made through
Iron is the fourth most abundant element in the Earth’s crust. Because it is so common, iron has been used by human society for thousands of years. Iron was known and used for weapons in prehistoric ages, the earliest example still in existence; a group of rusty iron beads found in Egypt, dates from about 4000BC. This period in history was given the name Iron Age because it was the time when people found ways to get iron and to use it for building tools and weapons.
The micro hardness of the prepared samples were obtained by using a Vickers Micro hardness Tester (Model : Leco LV 700, USA). 5 readings were taken for each sample to calculate the average hardness. An indentation load of 5gf was used. After calculating the average hardness for each sample, mean variance and standard deviation (S.D.) was calculated to check the consistency of the data.
As the name of the period suggests the Bronze Age brought forth the use of metals to construct various tools as well as weapons, bringing us to a second innovation during this historical period (Matthews et. al., 2014). It is thought that the Sumerians were the first to add tin to copper creating bronze in order to build stronger tools and weapons, estimated to have occurred around 3300 B.C. (History.com, 2018). This discovery brought an end to the Stone Age where previous tools and weapons had been chiseled from rock. The use of bronze spread to Greece, China, and the British Isles after a period of time.
Aluminum is one of a number of soft metals that scientists call "poor" metals. It can be shaped and twisted into any form. It can be rolled into thick plates for armored tanks or into thin foil for chewing gum wrappers. It may be drawn into a wire or made into cans. Aluminum is a generally popular metal because it does not rust and it resists wear from weather and chemicals. (Bowman, 391) Aluminum is an element. Its atomic number is thirteen and its atomic weight is usually twenty-seven. Pure aluminum melts at 660.2ºC and boils at 2500ºC. Its density is 2.7 grams per cube centimeter. Aluminum is never found uncombined in nature. (Bowman, 391) Aluminum is a very useful metal that is light, easy to shape and can be strong. This makes aluminum one of the most used metals in the world, right behind iron and steel. (Geary, 185) In its pure state, aluminum is quite weak compared to the other metals. However, its strength can be greatly increased by adding small amounts of alloying elements, heat-treating, or cold working. Only a small percentage of aluminum is used in its pure form. It is made into such items as electrical conductors, jewelry, and decorative trim for alliances and cars. A combination of the three techniques has produced aluminum alloys that, pound for pound, are stronger than structural steel. Some common metals used in alloys for aluminum are copper, magnesium and zinc.(Walker, 31) The added elements give the aluminum strength and other properties. (Newmark, 41) Aluminum is one of the lightest metals. It weighs about 168.5 pounds per cubic foot, about a third as much as steel which weighs 487 pounds per cubic foot. (Neely, 214) As a result, aluminum has replaced steel for many uses. For example, some ...
Some steel containers are made through deforming the steel by means of extruding, forging, spin forming, ...
Aluminum is an element in the boron group with a symbol of Al, and an atomic number of 13. Aluminum is a very soft metal when pure but becomes strong and hard when alloyed, a malleable metal with a silvery gray color. Aluminum is a very reactive element so it is found in nature combined with other elements. Aluminum resists corrosion by the formation of a self-protecting oxide coating. Aluminum is the third most abundant element in the Earth’s crust, following oxygen and silicon. It makes up approximately 8% by weight of the Earth’s surface. Although this is evident, it is also apparent that aluminum is never found by itself in nature. All of the earth’s aluminum has combined with other elements to form compounds and in order to create new aluminum products; it has to be taken out of that specific compound. Aluminum does not rust like other elements, therefore it always remains strong and shiny, which means reused aluminum is almost identical to a brand new piece of metal. An electrochemical process creates aluminum. An electrochemical process is “the direct process end use in which electricity is used to cause a chemical transformation” ( E.I.A. Government). Major uses of electrochemical processes occur in the aluminum industry in which alumina is reduced to molten aluminum metal and oxygen, where than the aluminum can be used into making several different materials. Electrochemical processes, although very useful, can have serious environmental consequences. To help reduce the consequences that the production of aluminum creates, the idea of aluminum recycling comes into play.
Metals possess many unique fundamental properties that make them an ideal material for use in a diverse range of applications. Many common place things know today are made from metals; bridges, utensils, vehicles of all modes of transport, contain some form of metal or metallic compound. Properties such as high tensile strength, high fracture toughness, malleability and availability are just some of the many advantages associated with metals. Metals, accompanied by their many compounds and alloys, similar properties, high and low corrosion levels, and affects, whether negative or positive, are a grand force to be reckoned with.
Toughness is the ability of a metal to mutilate plastically and to absorb energy in the process before it breaks or fracture. Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. This can be done by using heat treatment processes which include precipitation strengthening, quenching, annealing and tempering. Annealing and tempering are the most prominent methods for treating metals. A material may become more or less brittle, harder or softer, or stronger or weaker, depending on the treatment used.