The Ag-Cu phase diagram is that of a typical binary eutectic system. The melting temperatures for Ag and Cu are 960 and 1083 C, respectively, and the eutectic temperature is 779C. The eutectic composition is 28.1wt% Cu. At the eutectic temperature, the solubility limit of Ag in solid fcc-Cu is 8.8wt% and that of Cu in solid fcc-Ag is 8.0wt%. Consider a Ag-Cu alloy containing 51wt% Ag that is very slowly cooled though its freezing range. What is the primary phase? What are the fractions of the primary phase at 830 C and in the as-solidified microstructure, respectively?