Amorphous alloys definition

The second type of impurity, substitution of a lattice atom with an impurity atom, allows us to enter the world of alloys and intermetallics. Let us diverge slightly for a moment to discuss how control of substitutional impurities can lead to some useful materials, and then we will conclude our description of point defects. An alloy, by definition, is a metallic solid or liquid formed from an intimate combination of two or more elements. By intimate combination, we mean either a liquid or solid solution. In the instance where the solid is crystalline, some of the impurity atoms, usually defined as the minority constituent, occupy sites in the lattice that would normally be occupied by the majority constituent. Alloys need not be crystalline, however. If a liquid alloy is quenched rapidly enough, an amorphous metal can result. The solid material is still an alloy, since the elements are in intimate combination, but there is no crystalline order and hence no substitutional impurities. To aid in our description of substitutional impurities, we will limit the current description to crystalline alloys, but keep in mind that amorphous alloys exist as well. 

In [6.41-43] we find reports of the experimental investigations of partial distribution functions of atoms in amorphous alloys. The strong LO is discovered in the alloys of the metal-metalloid and metal-metal types. The compositional order is closely (but not always unambiguously) connected with the topological order, so that the presence of the former testifies to the existence of the definite local topological order. 

Another factor that has been claimed to influence the electrocatalytic properties of materials is the degree of crystallinity [52]. In particular, metals and metal alloys in an amorphous state have attracted interest as electrocatalysts for H2 evolution. In practice, amorphization is promoted by adding a non-metal such as B or P. However, evident effects are minor and there is no definitive proof that such an approach is worth practical consideration. Moreover, recrystallization of materials may take place under operating conditions [27]. 

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