Question

Additional Problem 1: Consider the following binary phase diagram for the Cu-Ni system at 1 atm pressure (a) For XNfotal 0.3 at 1500 K, find XNt and Xw°, and estimate f and f (b) Starting from XNfotal = 0.3 at 1500 K, the system is cooled, and a (Cu,Ni) solid solution forms. Find XNi for the last drop of the liquid as it crystallizes Ni 10 TГ Cu - Ni 20 30 40 50 60 70 80 90 wt% 1800 K 1728 K 1700 1600 L 1500 (Cu, Ni) 1400 1357.87K 1300 Cu 20 90 at% Ni Ni 80 70 60 50 40 30 10

Answer 1

Mole Fraction of Ni initially = 0.3 (Point A) To find Mole Fraction of Ni in Liquid phase, go horizontally left till it touches the liquid curve (Point B) Mole Fraction of Ni in liquid phase (Xi) = 0.27 To find Mole Fraction of Ni in Solid phase, go horizontally right till it touches the solid curve (Point C) Mole Fraction of Ni in solid phase (XSni) = 0.4 To find relative amount of each phase, we need to use Lever Rule. Lever Rule states, Amount of Solid phase Amount of Liquid phase Mole Fraction of Ni initially-Mole Fraction of Ni in liquid phase Mole Fraction of Ni in Solid phase-Mole Fraction of Ni initially 0.3 -0.27 0.4-0.3 = 0.3 Thus, Fraction of solid (t) = 133 = 0.2308 1+0.3 Thus, Fraction of liquid. (F4 = 72 = 0.7692 (b) Again, the initial point is point A. When the solution begins to cool, it follows vertically downward line till it intersects solid line at point D. To find composition of last drop of liquid, go horizontally left till it touches the liquid curve (Point E) = Composition of Ni at Point E Thus, Xni for last drop of liquid 30 % 0.19

Additional Problem 1: Consider the following binary phase diagram for the Cu-Ni system at 1 atm pressure. (a) For Xnfotal = 0.3 at 1500 K, find Xnt and XNS, and estimate fandfs. (b) Starting from Xni total = 0.3 at 1500 K, the system is cooled, and a (Cu,Ni) solid solution forms. Find Xn for the last drop of the liquid as it crystallizes. 10 20 30 40 50 60 70 80 90 wt% Cu-Ni 172RK (Cu, Ni) 1357.87K 13004 Cu 10 20 30 40 50 Ni — 60 70 80 90 ct % Ni