Based on the copper-zinc (Cu-Zn) phase diagram (Cu-Zn alloys are also called brass) shown below, answer the following questions. 20 30 30 (Wt % Zn) 40 40 50 60 70 20 60 80 80 90 00 10 20 1100 1000 900 800 T(°C) 700 a or (Cu) 600 500 400 3 Liquid 300 200 100 1 o 0 10 20 30 30 40 50 60 Cu Atom % Zn 70 20 F or (Zn) 80 80 90 100 Zn 85 1) In above Cu-Zn phase diagram, how many one phase, two phases and three phases fileds exist? (Hint: phase transformation occurs at a particular composition point in phase diagram is regarded as 3-phase coexisting). Use a table to list all the phases. 2) There are several temperatures where a phase of composition can transform to other phase(s) of different compositions as the alloy is cooled. Circle the composition and temperatures of the phases in red colour that phase transformation occurs on cooling (if you prefer, you can just write out the temperature and compositions of the phase that can transform to other phases). What are the generic names of the transformations? And write out the transformation reactions. 3) If the brass contains Copper 60 wt% and Zinc 40 wt%, and the constitution at room temperature is the same as at 200°C. Then at room temperature: 3a) What phase(s) are present in the brass? 3b) List the approximate phase composition(s) 3c) Calculate approximately the mass proportions of each phase. 4) If analysis of the brass indicates that the alloy contains 2.12 kg Zn and 1.88 kg Cu at 500°C. Calculate: 4a) the phase compositions 4b) the mass fractions of the phases for the alloys 5) If the brass is a 32 wt% Cu-68 wt% Zn alloy, make schematic sketches of the microstructure that would be observed for conditions of very slow cooling to the following temperatures: 1000°C, 760°C, 600°C and 400°C. Label all phases and indicate their approximate compositions.