Question

Metal A (melting point, 1050 K) and metal B (675 K) have two eutectic points. One is 641 K (3.2 % A weight fraction). Another is at 520 K (49% A weight fraction). There is a maximum melting point of AB alloy at 15.7 % weight fraction). (a) Drawing AB phase diagram with T-x and labelling all the possible phases. (15 Marks) (2) Please point out the phase transformation of the mixtures at 75% A and 30% A from 974 K cooling down to 573 K. In addition, using phase rule to describe the transformation (10 Marks). (3) Sketch the cooling curve of the mixture at 30% A.(5 Marks).

Answer 1

2 So_3(g) useriseto 2 So_2(g) + O_2(g) [So_3] = 0.620/2 = 0.310 M [O_2] = .100/2 = .050 M. 2So_3(g) 0.310 -2x 0.310-2x useriseto 2 So_2(g) 0 +2x 2x + O_2 (g) 0 +x. x. [O_2] = x = 0.050 M. K_C = [O_2] [SO_2]^2/[SO_3]^2 = (0.050) (0.100)^2/(0.210)^2 K_C = 0.01133 = 1.13 times 10^-2