(a) What is the difference between the states of phase equilibrium and metastability?

An alloy consisting of completely soluble cadmium (Cd) and zinc (Zn) in the liquid state, but neither of them dissolves in each other in the solid state. the table shown below shows the solidification temperatures for various alloys of cadmium and zinc. 1. Draw the equilibrium diagram according to the information given and data in the table and indicating all important temperature and phases. 2. Find the percentage of each phases and percentage of constituents of the alloy that contain 60 % Zn and at a temperature 300 °C. 3. Find the melting point for the following alloys 20 % Cd, 80% Cd 4. Draw the internal structure, noting the phases of the following alloys A) 30 % Cd at 290 °C b) 60 % Cd at room temperature. % of Zinc in alloy Start of solidification ("C) End of solidification ("C) 0 10 14 20 30 40 50 60 321 290 266 275 293 310 328 345 70 80 90 100 362 390 401 419 266 266 266 266 266 266 266 266 266 266 266 266

Is it possible to have a copper-nickel alloy that, at equilibrium, consists of a liquid phase of composition 20 wt% Ni-80 wt% Cu and also an a phase of composition 37 wt% Ni-63 wt% Cu? If so, what will be the approximate temperature of the alloy? If this is not possible, explain why. Temperature (°C) 1600 1500 1400 1300 1200 1100 1000 0 1085°C (Cu) 20 Liquid Liquidus line L B 40 a+L a A 60 Composition (wt% Ni) (a) 1455°C Solidus line 80 2800 2600 2400 2200 2000 100 (Ni) Temperature (°F) Temperature (°C) 1300 1200 20 Liquid Tie line. a + Liquid a 1 KR I 1 1 B ↑ Co a + Liquid -S 30 CL Composition (wt% Ni) (b) 40 1 Ca a 50

Consider 2.0 kg of austenite containing 0.5 wt% C and cooled to just below 727°C (1341°F).      (a)  What is the proeutectoid phase?      (b)  How many kilograms each of pearlite, the proeutectoid phase, and cementite form?