Question

(12 Question 2: points: 4 pts each) For a Lead-Tin (Pb-Sn) alloy of composition 85 wt% Sn - 15 wt % Pb and at 182 °C determine the followings: Show your calculation details in your answer and draw lines on the phase diagram to label the phases and compositions. a) Determine the mass fractions of a and B phases. b) Determine the mass fractions of primary B and eutectic microconstituents. c) Determine the mass fraction of eutectic B. Composition (at% Sn) 20 40 60 80 100 327°C -600 300 Liquid 500 232°C 200 9 BL 4400 183" Temperature (°C) Temperature (°F) 18.3 61.9 97.8 1300 100 4 + B 200 100 og 20 40 60 80 100 (Pb) Composition (wt% Sn) (Sn)

Answer 1

182°C 97.8 (18.3% 85%! a 61.9% ß -Eutectic (a) fachon of a, Xa= 97.8-85 97.8-18.3 = 0.161 fraction of ß, Xp= - |- Xa = – 0.7 6 | = 0.839 (6) fraction of primary XpB = 978-85 = 0.357 97.8-61.9 frachts of eutectic Xeu - - XPB - |- 0.3s4=0. 643 ( 0 ) Fraction of Eutectic ß Xep = Xp - Xpp 0.839 – 0.357 а Хер = 0.482