Читать книгу Solid State Chemistry and its Applications - Anthony R. West - Страница 36

Alloys are intermetallic phases or solid solutions and, as is the case for pure metals, many have cp structures. For example, Cu and Au have ccp structures, both as pure elements and when mixed to form Cu–Au alloys. At high temperatures, a complete range of solid solutions between Cu and Au forms. In these the Cu and Au atoms are distributed statistically over the lattice points of the fcc unit cell and therefore the ccp layers contain a random mixture of Cu and Au atoms. On annealing the compositions AuCu and AuCu₃ at lower temperatures, the Au and Cu atoms order themselves; ccp layers still occur but the arrangement within the layers is no longer statistical. Such order–disorder phenomena occur commonly in both metallic and ionic structures.

Table 1.3 Structures, unit cell dimensions, and metallic radii of some common metals