Question

4) Below is the phase diagram for Pb-Sn alloy. a) At 200 C°, determine the phases present at 10%Sn, 40%Sn and 80%Sn. (5 pts) b) At 200 C°, determine the composition of the phases for each weight percentage in (a). (5 pts) c) At 200 C°, determine the relative amount of each phase (weight fractions) for these points (5 pts) d) If you start cooling the system from 300 C° to 100 C°, what differences do you expect in the final system's microstructure for the alloys with 40% Sn, 80%Sn and 61.9% Sn. (10 pts) T(°C) 300 L (liquid) Lta 200 a L+BAB 183° 100 a +B 0 20 100 60 80 C, wt% Sn WW

Answer 1

Solution a) At 200°C 10% su, Phases present x-thape present are → 40 % Sn, phases present Liquid chase &- phase + 80 % Sn, Liquid phase phases present are : + ß- phase

b). composition of phapes present L- phave 19 wt % Su Liquid phase 61.9 wt %. In ß- flase 97.5 wt% su. c). Weight fractions :) 10% su 100 % a phase present *). 40% In We 40/42 40 - 19 6.0 61.9- 19 WL = 0.4895 wa 1 Wr. Wx= 0.5105 117 go %. Su WL = 97.5- 80 975 - 61.9 37 | up = 0.4916 Wp = 0.5084 We = - We