Solid solutions

A single crystal of two metals can be formed by melting two metals and subsequent crystallization. In such a crystal, unit cell will have both the metal atoms. Such a structure is called solid solution. In random substitutional solid solution, solute atoms have substituted randomly for the parent atoms on their sites. The arrangement of the solute and the solvent atoms are in a perfect order. In interstitial solid solution, solute atoms are selected in such a way that it is very much smaller than the parent atoms and can occupy interstitial voids between parent atoms. In face centered cubic crystal, these voids are called octahedral voids or tetrahedral voids.