ABSTRACT
But we can learn a lot more from this map (phase diagram). If we construct a horizontal line (a tie line) at the 600°C temperature, through our point of interest until we reach the phase boundary lines, we can obtain the composition of each phase (i.e., the maximum and minimum solubility limits of zinc in both the a and !3 phases respectively). Remember, the overall system composition is 40% Zn-60% Cu, but the composition of the two phases differ from this overall composition. Now if we drop vertical lines from each point of intersection of the phase boundaries with the horizontal tie line, we can read the composition of each phase, that of the alpha being 63.1 Cu-36.9 Zn and the beta 55.9 Cu-44.1 Zn. From this horizontal line and the compositions of each phase, we can also compute the quantities of each phase within the system. We will hold this computation for the Cu-Ni system, which is covered in the following section.
