Homework 11

Homework 11 - α liquid phase region If the mass fraction...

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Homework #11 ENME 382/ENMA 300 Due: Monday, December 5, 2011 1. For each of the following alloys: i) Cite the phases that are present and the phase compositions for each of the phases and ii) determine the relative amounts (in terms of mass fractions) of each of the phases at the given temperature: (a) 25 wt% Pb–75 wt% Mg at 425°C (800°F) (b) 55 wt% Zn–45 wt% Cu at 600°C (1110°F) (c) 7.6 lb m Cu and 144.4 lb m Zn at 600°C (1110°F) (d) 4.2 mol Cu and 1.1 mol Ag at 900°C (1650°F) 2. A 50 wt% Ni–50 wt% Cu alloy is slowly cooled from 1400°C (2550°F) to 1200°C (2190°F). (a) At what temperature does the first solid phase form? (b) What is the composition of this solid phase? (c) At what temperature does the liquid solidify? (d) What is the composition of this last remaining liquid phase? 3. A 40 wt% Pb – 60 wt% Mg alloy is heated to a temperature within the
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Unformatted text preview: α + liquid phase region. If the mass fraction of each phase is 0.5, then estimate: (a) The temperature of the alloy (b)The composition of each of the two phases 4. For a lead–tin alloy of composition 80 wt% Sn–20 wt% Pb and at 180°C (355°F) do the following: (a) Determine the mass fractions of and β phases. (b) Determine the mass fractions of primary and eutectic microconstituents. (c) Determine the mass fraction of eutectic . 5. For a 64 wt%Zn – 36 wt%Cu alloy, make schematic sketches of the microstructures that would be observed for conditions of very slow cooling at the following temperatures: 900°C (1650°F), 820°C (1510°F), 750°C (1380°F), and 600°C (1100°F). Label all phases and indicate their approximate compositions....
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