Question

2. For the Cu-Ag phase diagram, answer the following. Label the figure and add is part of your answer sheet....... .........(11 points) a) What is the eutectic temperature and composition? (1 point) b) In the context of this diagram, what does the symbol B represent? (1 point) c) Assume slow cooling and that equilibrium conditions exist for the alloy for 70 wt% Ag - 30 wt% Cu. If this is being cooled from 1000 °C, when will the first solid form and what composition would the solid have. (2 points) d) At the same composition listed above, List all the phases and their compositions at 600 °C. (2 points)

Answer 1

a) * The eatectie reaction cooling L a + B : Heating silver system, 719°C eutectie temperature 71.9 wt% Ag for the copper composition The B-phase is a solid solution rich in silver, it has copper the solute component It has FCL Structure, 729 6ooc 2.bg Wt%Ag to tlig 96. At, T=7799 The first solid is form. composition 2/8 wt%.Ag = C.. of solid x phase. d) Two phase d+B: compositrin, Cd=216 wt7.ag 9 = 96 wt 7. Ag.

Composition (at% Ag) 20 40 60 80 100 2200 1200 А 2000 -Liquidus 1000 Liquid 1800 F Solidus a +L 1600 800 779°C (Te) E BUL a G 11.9 B 1400 8.0 (Cae) Temperature (°C) 91.2 (CBE) Temperature (°F) IC 1200 600 Solvus 1000 a + B 800 400 600 H 20 40 60 400 96 100 70 80 200 2.6 (Cu) Composition (wt% Ag) (Ag)