An amorphous metal (also known as metallic glass, glassy metal, or shiny 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.
There are several ways in which amorphous metals can be produced, including extremely rapid cooling, physical vapor deposition, solid-state reaction, ion irradiation, and mechanical alloying.[1][2] Previously, small batches of amorphous metals had been produced through a variety of quick-cooling methods, such as amorphous metal ribbons which had been produced by sputtering molten metal onto a spinning metal disk (melt spinning). The rapid cooling (in the order of millions of degrees Celsius a second) is too fast for crystals to form and the material is "locked" in a glassy state.[3] Currently, a number of alloys with critical cooling rates low enough to allow formation of amorphous structure in thick layers (over 1 millimetre or 0.039 inches) have been produced; these are known as bulk metallic glasses. More recently, batches of amorphous steel with three times the strength of conventional steel alloys have been produced. New techniques as 3D printing, also characterised by their high cooling rates, are an active research topic for manufacturing bulk metallic glasses.[4]
- ^ Some scientists only consider amorphous metals produced by rapid cooling from a liquid state to be glasses. Materials scientists commonly consider a glass to be any solid non-crystalline material, regardless of how it is produced.
- ^ Ojovan, M. I.; Lee, W. B. E. (2010). "Connectivity and glass transition in disordered oxide systems". Journal of Non-Crystalline Solids. 356 (44–49): 2534. Bibcode:2010JNCS..356.2534O. doi:10.1016/j.jnoncrysol.2010.05.012.
- ^ Luborski, F E (1983). Amorphous Metallic Alloys. Butterworths. pp. 3–7. ISBN 0408110309.
- ^ Zhang, Cheng; Ouyang, Di; Pauly, Simon; Liu, Lin (2021-07-01). "3D printing of bulk metallic glasses". Materials Science and Engineering: R: Reports. 145: 100625. doi:10.1016/j.mser.2021.100625. ISSN 0927-796X. S2CID 236233658.