1. A 50 wt% Pb-50 wt% Mg alloy is slowly cooled from 700C (1290F) to 400C (750F). (a) At what temperature does the first solid phase form? (b) What is the composition of this solid phase? (c) At what temperature does the liquid solidify? (d) What is the composition of this last remaining liquid phase? [10 marks I Composition (at% Pb) 0 10 20 30 40 70 100 700 First (21 Wh Pb) 1200 600 Z 560C Mapo 1000 500 465C e 800 400 Temperature (C) Laliquid (67 win66) Temperature (- MePb 300 600 200 400 Mga Pb 100 Mga Pb 200 Mg, Pb 20 40 60 80 100 (M) Composition (wt% Pb) (Pb)