1. Amorphous Metal Alloys Kevin Allen MATERIAL SCIENCE MEEN 3344

2. What Are Amorphous Metal Alloys? An amorphous metal is a solid metallic material, usually an alloy, with a disordered atomic-scale structure. Amorphous metals also have a non-crystalline structure. (1) Amorphous metals are actually a combination of metals and metalloids consisting of mostly palladium, with a small fraction of silver and a smattering of other elements. This type of material actually closely resemble glass than regular metal. ( 10) (1) (2)

3. Properties The alloys contain atoms of significantly different sizes, which results in a higher viscosity when melted. (1) There are no grain boundaries (defects) present in the metal. (1) There is no shrinkage when cooled resulting in a resistance to plastic deformation. (1) When casted into solid shapes, amorphous metals have a high yield strength, higher hardness, and a higher strength/weight ratio than other metals. (8) (4) (3)

4. How It’s Made In the past, small batches of amorphous metals have been produced through a variety of quick-cooling methods. Amorphous metal wires were melted down and sputtered onto a spinning metal disk. This is called metal spinning. (1) Recently a number of alloys with critical cooling rates low enough to allow formation of amorphous structure in thick layers are added together to form a bulk mass of metal. This allows the metal to be mass produced. (1)

5. Advantages/Disadvantages It is 2-3 times the strength and hardness of both stainless steel and titanium. (8) Amorphous metal alloys are resistance to wear and corrosion. They are also much tougher and less brittle than oxide glasses and ceramics. (1) Despite several positive traits of metallic glasses, several limitations of the material still exist. Due to its high strength, it generally exhibits a low elastic strain limit. The material will not deform under load, but rather fail catastrophically when the fracture stress is reached. This can be dangerous in structural application because few visual cues are given if the material is about to fail. (9) Various process for producing metallic glasses are still in their infancy, so adoption and therefore production of the material is not yet wide spread. Production costs are far higher than conventional crystalline alloys so they are limited to applications. (9)

6. Applications These metals are found in newer golf clubs, tennis racquets, baseball bats, and diving watches (scuba gear). (6) Apple also purchased rights to use special amorphous pieces developed by Liquid Metal Technologies to use in their new MacBooks, wireless antennas, and other apple devices. (7) Amorphous metal alloys are also used in Kinetic Energy Penetrator (KEP) ammunition. A type of amour piercing of ammunition which, like a bullet, does not contain explosives and uses kinetic energy to penetrate the target. (5,11) (6) (7) (5)

7. References 1.http://en.wikipedia.org/wiki/Amorphous_metalhttp://en.wikipedia.org/wiki/Amorphous_metal 2.http://en.wikipedia.org/wiki/Crystalhttp://en.wikipedia.org/wiki/Crystal 3.http://en.wikipedia.org/wiki/Grain_boundaryhttp://en.wikipedia.org/wiki/Grain_boundary 4.http://lifeboat.com/ex/10.futuristic.materialshttp://lifeboat.com/ex/10.futuristic.materials 5.http://en.wikipedia.org/wiki/Kinetic_energy_penetratorhttp://en.wikipedia.org/wiki/Kinetic_energy_penetrator 6.http://www.msichicago.org/whats-here/exhibits/science-storms/the-exhibit/artifacts/atoms/amorphous-metal-golf-club-and-bat/http://www.msichicago.org/whats-here/exhibits/science-storms/the-exhibit/artifacts/atoms/amorphous-metal-golf-club-and-bat/ 7.http://arstechnica.com/apple/2010/08/amorphous-metal-alloys-to-slip-into-apple-products-soon/http://arstechnica.com/apple/2010/08/amorphous-metal-alloys-to-slip-into-apple-products-soon/ 8.http://www.liquidmetal.comhttp://www.liquidmetal.com 9.http://www.appropedia.org/Amorphous_Metal_Alloyshttp://www.appropedia.org/Amorphous_Metal_Alloys 10.http://www.futurity.org/science-technology/metallic-glass-thats-strong-and-tough/http://www.futurity.org/science-technology/metallic-glass-thats-strong-and-tough/ 11.http://www.defense-update.com/products/digits/120ke.htmhttp://www.defense-update.com/products/digits/120ke.htm