Interpretation of Phase Diagrams
9.8 This problem asks that we cite the phase or phases present for several alloys at specified temperatures. (a) For an alloycomposed of 15 wt% Sn-85 wt% Pb and at 100°C, from Figure 9.8, α and β phases are present, and Cα = 5 wt% Sn-95 wt% Pb Cβ = 98 wt% Sn-2 wt% Pb (b) For an alloy composed of25 wt% Pb-75 wt% Mg and at 425°C, from Figure 9.20, only the α phase is present; its composition is 25 wt% Pb-75 wt% Mg. (c) For an alloy composed of 85 wt% Ag-15 wt% Cuand at 800°C, from Figure 9.7, β and liquid phases are present, and Cβ = 92 wt% Ag-8 wt% Cu CL = 77 wt% Ag-23 wt% Cu (d) For an alloy composed of 55 wt% Zn-45 wt% Cu andat 600°C, from Figure 9.19, β and γ phases are present, and Cβ = 51 wt% Zn-49 wt% Cu Cγ = 58 wt% Zn-42 wt% Cu
(e) For an alloy composed of 1.25 kg Sn and 14 kg Pb andat 200°C, we must first determine the Sn and Pb concentrations (using Equation 4.3), as
1.25 kg × 100 = 8.2 wt% 1.25 kg + 14 kg 14 kg × 100 = 91.8 wt% 1.25 kg + 14 kgCSn =
C Pb =
From Figure 9.8, only the α phase is present; its composition is 8.2 wt% Sn-91.8 wt% Pb. (f) For an alloy composed of 7.6 lbm Cu and 144.4 lbm Zn andat 600°C, we must first determine the Cu and Zn concentrations (using Equation 4.3), as
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