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'''Amorphous metals can be grouped either as non-ferromagnetic, if they are composed of Ln, Mg, Zr, Ti, Pd, CA, Cu, Pt and Au, or ferromagnetic alloys, if they are composed of Fe, Co, and Ni. '''

 https://doi.org/10.1016/j.actamat.2010.11.027 

Taken from a study of all bulk glass alloys known up to 1993, bulk glass alloys were found to share three characteristics: consist of three elements or more, have a 12% or greater mismatch between the primary elements, and have negative enthalpy of mixing among the primary elements.   Alloys following these three characteristics had densely packed atomic structures, which were different to their crystallized forms and had long-range homogeneity with attractive interaction.

2 https://doi.org/10.2320/matertrans1989.36.1180

3 https://doi.org/10.1557/S0883769400053252 

4 https://doi.org/10.1016/S1359-6454(99)00300-6

5https://doi.org/10.1016/S0921-5093(00)01446-5

36

History Section
The first reported metallic glass was an alloy (Au75Si25) produced at Caltech by W. Klement (Jr.), Willens and Duwez in 1960.[3] This and other early glass-forming alloys had to be cooled extremely rapidly (on the order of one megakelvin per second, 106 K/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 micrometers.

In 1969, an alloy of 77.5% palladium, 6% copper, and 16.5% silicon was found to have critical cooling rate between 100 and 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.[4] This was an alloy of iron, nickel, phosphorus and boron. The material, known as Metglas, was commercialized in the early 1980s and is 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 °C and a room temperature saturation magnetization of 1.56 teslas.[5]

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.[clarification needed]

Research in Tohoku University[6] 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.[clarification needed]

'''In 1982, a study on amorphous metal structural relaxation indicated a relationship between the specific heat and temperature of (Fe0.5Ni0.5)83P17. As the material was heated up, the properties had a negative relationship starting at 375 K, which was due to the change in relaxed amorphous states. and when the material was annealed for periods from 1 to 48 hours, the properties had a postive relationship starting at 475 K for all annealing period, since the annealing induced relaxed structure disappears at that point. In this study, amorphous alloys demonstrated glass transition and a super cooled liquid region. Between 1988 and 1992, more studies searched for glass-type alloys with similar results. From those studies, bulk glass alloys made of La, Mg, and Zr showed plasticity when their ribbon thickness was increased from 20 μm to 50 μm. This behavior was a huge difference from past amorphous metals that became brittle at those thicknesses. '''

In 1988, alloys of lanthanum, aluminium, and copper ore were found to be highly glass-forming. Al-based metallic glasses containing Scandium exhibited a record-type tensile mechanical strength of about 1500 MPa.[7]

Before new techniques were found in 1990, creating bulk amorphous alloys of several millimeters was rare, except for a few exceptions, Pd-based amorphous alloys were formed into rods with a 2 mm diameter by quenching , and spheres with a 10 mm diameter was by repetition flux melting with B2O3 and then quenching it.

In the 1990s 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 four 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".

[1]https://doi.org/10.2320/matertrans1989.31.104

[7]https://doi.org/10.2320/matertrans1989.37.185

[8]https://doi.org/10.2320/matertrans.MF200622

[9] https://doi.org/10.1557/JMR.2008.0284

[29] https://doi.org/10.2320/matertrans1989.32.875

[23]https://doi.org/10.1016/0001-6160(69)90048-0

[24]https://doi.org/10.1063/1.95330

[25]Chen, H.S., Inoue, A. & Masumoto, T. J Mater Sci (1985) 20: 2417. https://doi.org/10.1007/BF00556071

Applications
Currently the most important application is due to the special magnetic properties of some ferromagnetic metallic glasses. The low magnetization loss is used in high efficiency transformers (amorphous metal transformer) at line frequency and some higher frequency transformers. Amorphous steel is a very brittle material which makes it difficult to punch into motor laminations.[19] Also electronic article surveillance (such as theft control passive ID tags,) often uses metallic glasses because of these magnetic properties.

Amorphous metals exhibit unique softening behavior above their glass transition and this softening has been increasingly explored for thermoplastic forming of metallic glasses.[20] Such low softening temperature allows for developing simple methods for making composites of nanoparticles (e.g. carbon nanotubes) and BMGs. It has been shown that metallic glasses can be patterned on extremely small length scales ranging from 10 nm to several millimeters.[21] This may solve the problems of nanoimprint lithography where expensive nano-molds made of silicon break easily. Nano-molds made from metallic glasses are easy to fabricate and more durable than silicon molds. The superior electronic, thermal and mechanical properties of BMGs compared to polymers make them a good option for developing nanocomposites for electronic application such as field electron emission devices.[22]

Ti40Cu36Pd14Zr10 is believed to be noncarcinogenic, is about three times stronger than titanium, and its elastic modulus nearly matches bones. It has a high wear resistance and does not produce abrasion powder. The alloy does not undergo shrinkage on solidification. A surface structure can be generated that is biologically attachable by surface modification using laser pulses, allowing better joining with bone.[23]

Mg60Zn35Ca5, rapidly cooled to achieve amorphous structure, is being investigated, at Lehigh University, as a biomaterial for implantation into bones as screws, pins, or plates, to fix fractures. Unlike traditional steel or titanium, this material dissolves in organisms at a rate of roughly 1 millimeter per month and is replaced with bone tissue. This speed can be adjusted by varying the content of zinc.[24]

Ti-based metallic glass, when made into thin pipes, have a high tensile strength of 2100 MPA, elastic elongation of 2% and high corrosion resistance. '''Using these properties, a Ti–Zr–Cu–Ni–Sn metallic glass was used to improve the sensitivity of a Coriolis flow meter. This meter is about 28-53 times more sensitive than conventional meters , which can be useful in fossil-fuel, chemical, environmental, semiconductor and medical science industry.'''

'''Zr-Al-Ni-Cu based metallic glass can be shaped into 2.2-5mm by 4mm pressure sensors for automobile and other industries, and are smaller, more sensitive, and possess greater pressure endurance compared to conventional stainless steel made from cold working. Additionally, this alloy were used to make the world's smallest geared motor with diameter 1.5mm and 9.9mm to be produced and sold at the time.'''

[117] https://doi.org/10.1557/mrs2007.128

[118]http://www.ipme.ru/e-journals/RAMS/no_11808/inoue.pdf

[120] https://doi.org/10.1016/j.jnoncrysol.2007.05.170

[121] https://doi.org/10.1016/j.msea.2006.02.384

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Sign feedback with DavidThi1 (talk) 17:47, 24 April 2019 (UTC) David Thi