T°C
a
b
c
d
e
f
8
9
500
400
1
300
X
Z
3
4
6
7
200
Y
2
5
100
A
AB
AB2
B
Mole fraction B (XB) ?
8. This is the phase diagram of the binary system A-B at 1 atm pressure.
a. What four phases are stable at 100°C?
b. What is the name of the horizontal line separating region 2 from
regions 1 and 3?
c. What are the approximate melting points of A and B?
d. What happens when you try to melt solid compound AB2?
e. List the phases that are present in regions 1-9.
f. Are any of these phases solid solutions?
g. Apply the Gibbs Phase rule for this 2-component phase diagram at 1
atm pressure at points a, w, x, y and z. State the number of
phases and degrees of freedom at each point.
h. List the phases that exist as you cool compositions indicated by a-
f from 580°C to room temperature.
i. Take composition e ($X_B$ = 0.65) and give the compositions of the
phases at 500°, 400°, and 300°C.
j. For composition e ($X_B$ = 0.65), what is the relative amount of
liquid and solid at 500°, 400°, and 300°C?
k. Both compositions e and f experience a peritectic reaction. What
is the difference in the outcome for e vs. f?
