Wednesday, July 29, 2009

Amorphous metal for aluminium alloy ingots

I want to introduct something about Display Case. Display Case The front arc-shaped double layer glass and the defogged(built-in heated)devices make the display cases have a wider front view; the stainless steel frame gives you a stylish and elegant-impression. The extraordinary moisture-generated device keep the stored foods fresh,soft and attractive color. The product is equipped with import condensing units and sophisticated production technologies to ensure optimized refrigeration result and ideal quality. The average humidity can be up to 85%. The case bodies are made of the Hi-tech synthetic materials of simulated granites made in USA, which have even better effects than the natural granites with more options of color and patterns, higher density, free from dirt and grease, wear resistant, fire-proof, easier to repair when damaged. The product has been granted the certification of patent by the State, and the QC issued by Guangzhou Quality & Technology Inspection Authority.

Sample of amorphous metal in the lab
An amorphous metal is a metallic material with a disordered atomic-scale structure. In contrast to most metals, which are crystalline and therefore have a highly ordered arrangement of atoms, amorphous alloys are non-crystalline. Materials in which such a disordered structure is produced directly from the liquid state during cooling are called "glasses", and so amorphous metals are commonly referred to as "metallic glasses" or "glassy metals". However, there are several other ways in which amorphous metals can be produced, including physical vapor deposition, solid-state reaction, ion irradiation, melt spinning, and mechanical alloying. Amorphous metals produced by these techniques are, strictly speaking, not glasses; however, materials scientists commonly consider amorphous alloys to be a single class of materials, regardless of how they are prepared.
In the past, small batches of amorphous metals have been produced through a variety of quick-cooling methods. For instance, amorphous metal wires have been produced by sputtering molten metal onto a spinning metal disk. The rapid cooling, on the order of millions of degrees a second, is too fast for crystals to form and the material is "locked in" a glassy state. More recently a number of alloys with critical cooling rates low enough to allow formation of amorphous structure in thick layers (over 1 millimeter) had been produced, these are known as bulk metallic glasses (BMG). Liquidmetal sells a number of titanium-based BMGs, developed in studies originally carried out at Caltech. More recently, batches of amorphous steel have been produced that demonstrate strengths much greater than conventional steel alloys.
Contents
1 History
2 Properties
3 References
4 External links
5 See also
//
History
The first metallic glass was an alloy (Au75Si25) produced at Caltech by W. Klement (Jr.), Willens and Duwez in 1960 . This and other early glass-forming alloys had to be cooled extremely rapidly (on the order of one megakelvin per second, 106K/s) to avoid crystallization. An important consequence of this was that metallic glasses could only be produced in a limited number of forms (typically ribbons, foils, or wires) in which one dimension was small so that heat could be extracted quickly enough to achieve the necessary cooling rate. As a result, metallic glass specimens (with a few exceptions) were limited to thicknesses of less than one hundred micrometres.
In 1969, an alloy of 77.5% palladium, 6% copper, and 16.5% silicon was found to have critical cooling rate between 100 K/s to 1000 K/s.
In 1976, H. Liebermann and C. Graham developed a new method of manufacturing thin ribbons of amorphous metal on a supercooled fast-spinning wheel. This was an alloy of iron, nickel, phosphorus and boron. The material, known as Metglas, was commercialized in early 1980s and used for low-loss power distribution transformers (Amorphous metal transformer). Metglas-2605 is composed of 80% iron and 20% boron, has Curie temperature of 373 and a room temperature saturation magnetization of 125.7 milliteslas.
In the early 1980s, glassy ingots with 5 mm diameter were produced from the alloy of 55% palladium, 22.5% lead, and 22.5% antimony, by surface etching followed with heating-cooling cycles. Using boron oxide flux, the achievable thickness was increased to a centimeter.
The research in Tohoku University and Caltech yielded multicomponent alloys based on lanthanum, magnesium, zirconium, palladium, iron, copper, and titanium, with critical cooling rate between 1 K/s to 100 K/s, comparable to oxide glasses.
In 1988, alloys of lanthanum, aluminium, and copper ore were found to be highly glass-forming.
In the 1990s, however, new alloys were developed that form glasses at cooling rates as low as one kelvin per second. These cooling rates can be achieved by simple casting into metallic molds. These "bulk" amorphous alloys can be cast into parts of up to several centimeters in thickness (the maximum thickness depending on the alloy) while retaining an amorphous structure. The best glass-forming alloys are based on zirconium and palladium, but alloys based on iron, titanium, copper, magnesium, and other metals are also known. Many amorphous alloys are formed by exploiting a phenomenon called the "confusion" effect. Such alloys contain so many different elements (often a dozen or more) that upon cooling at sufficiently fast rates, the constituent atoms simply cannot coordinate themselves into the equilibrium crystalline state before their mobility is stopped. In this way, the random disordered state of the atoms is "locked in".
In 1992, the first commercial amorphous alloy, Vitreloy 1 (41.2% Zr, 13.8% Ti, 12.5% Cu, 10% Ni, and 22.5% Be), was developed at Caltech, as a part of Department of Energy and NASA research of new...(and so on) To get More information , you can visit some products about 17 inch laptop cases, ipod mini case, atx mini cases, cheap cd cases, dvd holder case, wholesale cell phone cases, shopping trolley bag, small computer cases, cd calendar cases, metal card cases, . The Display Case products should be show more here!

No comments:

Post a Comment