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    Amorphous alloy

    amorphous alloy

    When metals are heated above melting point together with ceramics and other materials, their atoms are stirred into random motion (Brownian motion). Once the material cools, it forms immediately a regular atomic lattice, such as children playing on the playground who form into a row when the teacher calls.

    In a naturally occurring environment, the formation of the crystalline lattice is not instantaneous. In the transition from the molten state into the solid state, the atoms of the metal or the ceramic material need a certain limited amount of time to assume their position in the order.

    In metals, this period is of the order of a hundred - thousandth or millionth of a second. The cooling rate is therefore 105-108 °C / sec. However, no exact figures are available on the topic in lack of appropriate scientific research. When the material is quenched at a faster cooling rate, it results in a transient state.

    This transient state is simultaneously polycrystalline like any ordinary metal and non- crystalline and is therefore referred to as amorphous alloy. Since such a rapid quenching is not practical to implement, Si or B (boron) are used as fill elements in order to achieve an amorphous state at a lower cooling rate. As the illustration shows, amorphous alloys are formed by pouring the melt onto a rapidly rotating drum where it turns into an extremely thin metal film. The alloys produced by this method possess 1) good mechanical properties, 2) high corrosion resistance, and 3) a high electrical resistance. Today they are used, among other purposes, in acoustic recording heads.