Question

Answer the following questions by referring to the Cu-Al phase diagram shown below.


(a) What is the lowest temperature at which a liquid can be found in a system of any composition of Cu-Al ?


(b) A common alloy composition used in airplanes is 4 at. % Cu - 96 at. % Al. For this overall system composition, identify what phases are present at 500 degrees C. Select all phases present:
Liquid
Vapor
Al
Cu
CuAl2
CuAl
Cu1.5Al
Cu9Al4
Cu4Al
Cu0.75Al0.25


(c) What phases are present at a 50/50 mixture of Al/Cu at 660 degrees C? Select all phases present:
Liquid
Vapor
Al
Cu
CuAl2
CuAl
Cu1.5Al
Cu9Al4
Cu4Al
Cu0.75Al0.25

(d) In the previous question, you should have identified two phases. What is the phase fraction of the first phase you identified?

Answer 1

(a) From 530 to 570.
(d) 0.41
any ideas for b)and c) ?

Answer 2

for (c) ans is liquid and Cu1.5Al

Answer 3

(B) Al & CuAl2

Answer 4

d = 0.41 how can i calculate that result?

Answer 5

The phase fraction is calculated using the 'Lever Rule'.

I can't figure out how to do it, but it involves using this formula-

X = (c-b)/(a-b)

Where a, b, and c are distances between x-coordinates at various phase boundaries.

But the phase diagram in this question is weird and I can't figure out where the points are so I don't know the distances required for the formula.