Stoichiometry percentage composition from

When melts of some metal mixtures solidify, the alloy formed may possess a definite lattice type that is difierent from those of the pure metals. Such systems are classified as intermetallic compounds, e.g. 3-brass, CuZn. At 298 K, Cu has a ccp lattice and Zn has a structure related to an hep array, but 3-brass adopts a bcc structure. The relative proportions of the two metals are crucial to the alloy being described as an intermetallic compound. Alloys labelled brass may have variable compositions, and the a-phase is a substitutional alloy possessing the ccp structure of Cu with Zn functioning as the solute. 3-Brass exists with Cu Zn stoichiometries around 1 1, but increasing the percentage of Zn leads to a phase transition to y-brass (sometimes written as Cu5Zng, although the composition is not fixed), followed by a transition to... 

Figure 13.17 shows that some compositions are common to almost all systems, while others correspond to single cases. The frequency of the various stoichiometries is represented in fig. 13.18, where the relative percentage of each composition is shown. From this histogram we can observe that four stoi-... 

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