Liquidmetal

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A USB flash drive with a Liquimetal case. SanDisk Cruzer Titanium 02.jpg
A USB flash drive with a Liquimetal case.

Liquidmetal and Vitreloy are commercial names of a series of amorphous metal alloys developed by a California Institute of Technology (Caltech) research team and marketed by Liquidmetal Technologies. Liquidmetal alloys combine a number of desirable material features, including high tensile strength, excellent corrosion resistance, very high coefficient of restitution and excellent anti-wearing characteristics, while also being able to be heat-formed in processes similar to thermoplastics. Despite the name, they are not liquid at room temperature. [1]

Contents

Liquidmetal was introduced for commercial applications in 2003. [2] It is used for, among other things, golf clubs, watches, and covers of cell phones.

The alloy was the end result of a research program into amorphous metals carried out at Caltech. It was the first of a series of experimental alloys that could achieve an amorphous structure at relatively slow cooling rates.[ citation needed ] Amorphous metals had been made before, but only in small batches because cooling rates needed to be in the millions of degrees per second. For example, amorphous wires could be fabricated by splat quenching a stream of molten metal on a spinning disk. Because Vitreloy allowed such slow cooling rates, production of larger batch sizes was possible. More recently, a number of additional alloys have been added to the Liquidmetal portfolio. These alloys also retain their amorphous structure after repeated re-heating, allowing them to be used in a wide variety of traditional machining processes.

Characteristics

Liquidmetal, created by Dr. Atakan Peker, contain atoms of significantly different sizes. They form a dense mix with low free volume. Unlike crystalline metals, there is no obvious melting point at which viscosity drops suddenly. Vitreloy behaves more like other glasses, in that its viscosity drops gradually with increased temperature. At high temperature, it behaves in a plastic manner, allowing the mechanical properties to be controlled relatively easily during casting. The viscosity prevents the atoms moving enough to form an ordered lattice, so the material retains its amorphous properties even after being heat-formed.

The alloys have relatively low softening temperatures, allowing casting of complex shapes without needing finishing. The material properties immediately after casting are much better than those of conventional metals; usually, cast metals have worse properties than forged or wrought ones. The alloys are also malleable at low temperatures (400 °C or 752 °F for the earliest formulation), and can be molded. The low free volume also results in low shrinkage during cooling. For all of these reasons, Liquidmetal can be formed into complex shapes using processes similar to thermoplastics, [3] which makes Liquidmetal a potential replacement for many applications where plastics would normally be used.

Due to their non-crystalline (amorphous) structures, Liquidmetals are harder than alloys of titanium or aluminum of similar composition. The zirconium and titanium based Liquidmetal alloys achieved yield strength of over 1723 MPa, nearly twice the strength of conventional crystalline titanium alloys (Ti6Al4V is ~830 MPa), and about the strength of high-strength steels and some highly engineered bulk composite materials (see tensile strength for a list of common materials). However, the early casting methods introduced microscopic flaws that were excellent sites for crack propagation which led to Vitreloy being fragile like glass. Although strong, these early batches shattered easily when struck. Newer casting methods, adjustments of the alloy mixtures and other changes have improved this.[ citation needed ]

The lack of grain boundaries contributes to the high yield strength (and thereby resilience) exhibited. In a demonstration, a metal sphere dropped on amorphous steel bounced significantly longer than the same metal sphere dropped on crystalline steel. [4]

The lack of grain boundaries in a metallic glass eliminates grain-boundary corrosiona common problem in high-strength alloys produced by precipitation hardening and sensitized stainless steels. Liquidmetal alloys are therefore generally more corrosion resistant, both due to the mechanical structure as well as the elements used in its alloy. The combination of mechanical hardness, high elasticity and corrosion resistance makes Liquidmetal wear resistant.

Although at high temperatures, plastic deformation occurs easily, almost none occurs at room temperature before the onset of catastrophic failure. This limits the material's applicability in reliability-critical applications, as the impending failure is not evident. The material is also susceptible to metal fatigue with crack growth. A two-phase composite structure with amorphous matrix and a ductile dendritic crystalline-phase reinforcement, or a metal matrix composite reinforced with fibers of other material can reduce or eliminate this disadvantage. [5]

Uses

Liquidmetal combines a number of features that are normally not found in any one material. This makes them useful in a wide variety of applications.

One of the first commercial uses of Liquidmetal was in golf clubs made by the company, where the highly elastic metal was used in portions of the club face. [6] These were highly rated by users, but the product was later dropped, in part because the prototypes shattered after fewer than 40 hits. [7] Since then, Liquidmetal has appeared in other sports equipment, including the cores of golf balls, skis, baseball and softball bats, and tennis racquets. [8]

The ability to be cast and molded, combined with high wear resistance, has also led to Liquidmetal being used as a replacement for plastics in some applications. [9] It has been used on the casing of late-model SanDisk "Cruzer Titanium" USB flash drives as well as their Sansa line of flash-based MP3 player, and casings of some mobile phones, like the luxury Vertu products, and other toughened consumer electronics.[ citation needed ] Liquidmetal was used in the Biolase dental laser Ilase [10] and the Socketmobile ring bar code scanner. Liquidmetal has also notably been used for making the SIM ejector tool of some iPhone 3Gs made by Apple Inc., shipped in the US. This was done by Apple as an exercise to test the viability of usage of the metal. [11] They retain a scratch-free surface longer than competing materials, while still being made in complex shapes. The same qualities lend it to use as protective coatings for industrial machinery, including petroleum drill pipes and power plant boiler tubes.[ citation needed ]

It also replaces titanium in applications ranging from medical instruments and cars to the military and aerospace industry. In military applications, rods of amorphous metals replace depleted uranium in kinetic energy penetrators. [12] Plates of Liquidmetal were used in the solar wind ion collector array in the Genesis space probe.[ citation needed ]

Commercial alloys

A range of zirconium-based alloys have been marketed under this trade name. Some example compositions are listed below, in molar percent:

Licensed uses

Related Research Articles

<span class="mw-page-title-main">Alloy</span> Mixture or metallic solid solution composed of two or more elements

An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, opacity, and luster, but may have properties that differ from those of the pure metals, such as increased strength or hardness. In some cases, an alloy may reduce the overall cost of the material while preserving important properties. In other cases, the mixture imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength.

<span class="mw-page-title-main">Glass</span> Transparent non-crystalline solid material

Glass is a non-crystalline solid that is often transparent, brittle and chemically inert. It has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics.

<span class="mw-page-title-main">Metal</span> Type of material

A metal is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically ductile and malleable. These properties are the result of the metallic bond between the atoms or molecules of the metal.

<span class="mw-page-title-main">Metallurgy</span> Field of science that studies the physical and chemical behavior of metals

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 known as alloys.

<span class="mw-page-title-main">Titanium</span> Chemical element, symbol Ti and atomic number 22

Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine.

<span class="mw-page-title-main">Brazing</span> Metal-joining technique

Brazing is a metal-joining process in which two or more metal items are joined by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal.

<span class="mw-page-title-main">Amorphous metal</span> Solid metallic material with disordered atomic-scale structure

An amorphous metal is a solid metallic material, usually an alloy, with disordered atomic-scale structure. Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms. Amorphous metals are non-crystalline, and have a glass-like structure. But unlike common glasses, such as window glass, which are typically electrical insulators, amorphous metals have good electrical conductivity and can show metallic luster.

Refractory metals are a class of metals that are extraordinarily resistant to heat and wear. The expression is mostly used in the context of materials science, metallurgy and engineering. The definition of which elements belong to this group differs. The most common definition includes five elements: two of the fifth period and three of the sixth period. They all share some properties, including a melting point above 2000 °C and high hardness at room temperature. They are chemically inert and have a relatively high density. Their high melting points make powder metallurgy the method of choice for fabricating components from these metals. Some of their applications include tools to work metals at high temperatures, wire filaments, casting molds, and chemical reaction vessels in corrosive environments. Partly due to the high melting point, refractory metals are stable against creep deformation to very high temperatures.

<span class="mw-page-title-main">Refractory</span> Materials resistant to decomposition under high temperatures

In materials science, a refractory is a material that is resistant to decomposition by heat or chemical attack that retains its strength and rigidity at high temperatures. They are inorganic, non-metallic compounds that may be porous or non-porous, and their crystallinity varies widely: they may be crystalline, polycrystalline, amorphous, or composite. They are typically composed of oxides, carbides or nitrides of the following elements: silicon, aluminium, magnesium, calcium, boron, chromium and zirconium. Many refractories are ceramics, but some such as graphite are not, and some ceramics such as clay pottery are not considered refractory. Refractories are distinguished from the refractory metals, which are elemental metals and their alloys that have high melting temperatures.

Plating is a finishing process in which a metal is deposited on a surface. Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish.

Titanium alloys are alloys that contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness. They are light in weight, have extraordinary corrosion resistance and the ability to withstand extreme temperatures. However, the high cost of both raw materials and processing limit their use to military applications, aircraft, spacecraft, bicycles, medical devices, jewelry, highly stressed components such as connecting rods on expensive sports cars and some premium sports equipment and consumer electronics.

<span class="mw-page-title-main">Magnesium alloy</span> Mixture of magnesium with other metals

Magnesium alloys are mixtures of magnesium with other metals, often aluminium, zinc, manganese, silicon, copper, rare earths and zirconium. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminium, copper and steel; therefore, magnesium alloys are typically used as cast alloys, but research of wrought alloys has been more extensive since 2003. Cast magnesium alloys are used for many components of modern automobiles and have been used in some high-performance vehicles; die-cast magnesium is also used for camera bodies and components in lenses.

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<span class="mw-page-title-main">Aluminium alloy</span> Alloy in which aluminium is the predominant metal

An aluminium alloy (UK/IUPAC) or aluminum alloy is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminium alloys yield cost-effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast aluminium alloy system is Al–Si, where the high levels of silicon (4–13%) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is required.

<span class="mw-page-title-main">Melt spinning</span>

Melt spinning is a metal forming technique that is typically used to form thin ribbons of metal or alloys with a particular atomic structure.

Vacuum arc remelting (VAR) is a secondary melting process for production of metal ingots with elevated chemical and mechanical homogeneity for highly demanding applications. The VAR process has revolutionized the specialty traditional metallurgical techniques industry, and has made possible tightly-controlled materials used in biomedical, aviation and aerospace.

<span class="mw-page-title-main">Solid</span> State of matter

Solid is one of the four fundamental states of matter along with liquid, gas, and plasma. The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural rigidity and resistance to a force applied to the surface. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire available volume like a gas. The atoms in a solid are bound to each other, either in a regular geometric lattice, or irregularly. Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because the molecules in a gas are loosely packed.

<span class="mw-page-title-main">Liquid metal</span> Metal or alloy that is liquid at room temperature

A liquid metal is a metal or a metal alloy which is liquid at or near room temperature.

Bioresorbablemetallic glass is a type of amorphous metal, which is based on the Mg-Zn-Ca ternary system. Containing only elements which already exist inside the human body, namely Mg, Zn and Ca, these amorphous alloys are a special type of biodegradable metal.

Splat quenching is a metallurgical, metal morphing technique used for forming metals with a particular crystal structure by means of extremely rapid quenching, or cooling.

References

  1. liquidmetal.com. Liquidmetal Coatings Material. Retrieved 2008-10-23 Archived January 31, 2009, at the Wayback Machine
  2. Herrman, J. (2010, August 17). Giz Explains: What Is Liquidmetal? Retrieved July 7, 2015.
  3. Liquid metal behaves like plastic, Manufacturing Engineering, March 2003 Archived 2005-12-06 at the Wayback Machine
  4. Official Liquidmetal Ball Bouncer Demonstration on YouTube
  5. The case for bulk metallic glass, Materials Today, March 2004
  6. Gorant, Jim (July 1998). "Liquid Golf". Popular Mechanics . Archived from the original on December 12, 2006.
  7. Catherine Zandonella (2005-04-02). "Metallic glass: A drop of the hard stuff". New Scientist no. 2493. Archived from the original on October 22, 2012. Retrieved 2013-06-10.
  8. Drivers -- Liquid Metal driver - discussion of Liquidmetal golf clubs
  9. American Institute of Physics. "When it comes to churning out electrons, metal glass beats plastics." ScienceDaily. 28 November 2011 (accessed November 21, 2015).
  10. "Biolase Dental Laser ILASE®". Biolase. 20 November 2018.
  11. "Liquidmetal created SIM ejector tool for Apple's iPhone, iPad". Appleinsider.com. 2010-08-17. Retrieved 2013-06-10.
  12. "Defense and Tactical Applications". Liquidmetal Technologies. Archived from the original on March 23, 2013. Retrieved 2012-05-24.
  13. Demetriou, Marios D; Johnson, William L (12 July 2004). "Shear flow characteristics and crystallization kinetics during steady non-isothermal flow of Vitreloy-1". Acta Materialia. 52 (12): 3403–3412. Bibcode:2004AcMat..52.3403D. doi:10.1016/j.actamat.2004.03.034.
  14. Morrison, M.L.; R.A. Buchanan; P.K. Law; B.A. Green; G.Y. Wang; C.T. Liu; J.A. Horton (15 October 2007). "Four-point-bending-fatigue behavior of the Zr-based Vitreloy 105 bulk metallic glass". Materials Science and Engineering: A. 467 (1–2): 190–197. doi:10.1016/j.msea.2007.05.066.
  15. "Apple Renews Exclusive Rights to Liquidmetal Technologies' Alloys". MacRumors. Archived from the original on July 12, 2016. Retrieved Feb 18, 2017.
  16. "Swatch Group signs Exclusive License Agreement with Liquidmetal Technologies". Press release. The Swatch Group. March 10, 2011. Retrieved 2013-06-10. Liquidmetal Technologies Inc. (OTCBB: LQMT) and The Swatch Group Ltd (SIX: Uhr / Uhr N) today announced that they have signed an exclusive licensing agreement, allowing the Swiss manufacturer to utilize the Liquidmetal alloy technology worldwide. Within the Swatch Group, the Liquidmetal technology has been used for the first time in 2009 for the Omega Seamaster Planet Ocean, and in 2010 for the Breguet «Reveil Musical». The present contract will allow the Swatch Group to use the technology exclusively in their entire line of timepieces.