Ciencias dos materias

9-8

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 alloy composed 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 of 25 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% Cu and 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 and at 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 and at 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 kg

CSn =

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 and at 600°C, we must first determine the Cu and Zn concentrations (using Equation 4.3), as
Excerpts from this work may be reproduced by instructors for distribution on a not-for-profit basis for testing or instructional purposes only to students enrolled in courses for which the textbook has been adopted. Any other reproduction or translation of this work beyond that permitted by Sections 107 or 108 of the 1976 United States Copyright Act without the permission of the copyright owner is unlawful.