Metallic glasses

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. Amorphous metals can be produced in several ways, including extremely rapid cooling, physical vapor deposition, solid-state reaction, ion irradiation, and mechanical alloying. Small batches of amorphous metals have been produced through a variety of quick-cooling methods, such as amorphous metal ribbons produced by sputtering molten metal onto a spinning metal disk (melt spinning). The rapid cooling (millions of degrees Celsius per second) comes too fast for crystals to form and the material is "locked" in a glassy state. Alloys with cooling rates low enough to allow formation of amorphous structure in thick layers (over 1 millimetre or 0.039 inches) have been produced; bulk metallic glasses. Batches of amorphous steel with three times the strength of conventional steel alloys have been produced. New techniques such as 3D printing, also characterised by high cooling rates, are an active research topic.