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Homework 11 Solutions

# Homework 11 Solutions - Homework#11 SOLUTIONS ENME 382/ENMA...

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Homework #11 SOLUTIONS 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) i) For an alloy composed of 25 wt% Pb-75 wt% Mg at 425 ° C, from Figure 10.20, only the α phase is present; its composition is 25 wt% Pb-75 wt% Mg. ii) For an alloy composed of 25 wt% Pb-75 wt% Mg at 425 ° C, only the α phase is present; therefore W α = 1.0. (b) 55 wt% Zn–45 wt% Cu at 600°C (1110°F) i)For an alloy composed of 55 wt% Zn-45 wt% Cu at 600 ° C, from Figure 10.19, β and γ phases are present,and C β = 51 wt% Zn-49 wt% Cu C γ = 58 wt% Zn-42 wt% Cu ii) Because the composition of the alloy, C 0 = 55 wt% Zn-45 wt% Cu, then, using the appropriate lever rule expressions and taking compositions in weight percent zinc (c) 7.6 lb m Cu and 144.4 lb m Zn at 600°C (1110°F) i) For an alloy composed of 7.6 lbm Cu and 144.4 lbm Zn and at 600 ° C, we must first determine the Cu and Zn concentrations (using Equation 5.6 OR first principles), as

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From Figure 10.19, only the L phase is present; its composition is 95.0 wt% Zn-5.0 wt% Cu ii) For an alloy composed of 7.6 lbm Cu and 144.4 lbm Zn (95.0 wt% Zn-5.0 wt% Cu) at 600 ° C,
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