# Homework Help: Phase diagram question

1. Mar 25, 2015

### mrblanco

THIS HOMEWORK WAS PLACED INCORRECTLY IN ANOTHER FORUM, SO THERE IS NO TEMPLATE (AND NO EFFORT)

I have no idea how to tackle this. Please show me how to do these problems.

Last edited by a moderator: Mar 26, 2015
2. Mar 26, 2015

### Pierce610

It seems to me that:

> y = temperature and x = molar fraction of Ni
> The phase diagram shows liquid and solid phases
> At 1000° and x(Ni)=0.5 , AlNi has a solid phase
This is only a brief suggestion; however let’s wait for an answer by an expert.

3. Mar 26, 2015

### Staff: Mentor

Mrblanco, You need to read the PF rules and guidelines. Before we can help you, there needs to be some effort on your part. Saying that you don't have a clue is not an acceptable answer. Tell us your understanding of how phase diagrams work, even if it is very little.

Chet

4. Mar 26, 2015

### mrblanco

Ok. So I understand how to get the phases present at each stage and I went ahead and labeled where each point should fall on, however, I don't understand how to get the composition of each phase or the amount of phases. Here is what I have so far:

And I was given part (d) as an example but it's honestly made the problem more confusing as I am just given answers and no way of determining them

5. Mar 26, 2015

### Staff: Mentor

It looks like there is something wrong with the solution sheet for part d. They correctly identified the phases present, and then calculated the proportions of the phases. But, in displaying the proportions, they mis-labeled Ni as Al3Ni2. They calculated the proportions by drawing a "tie line" and applying the "lever rule." Are you familiar with these concepts?

Chet

6. Mar 26, 2015

### mrblanco

Yes. I actually just had one of those "aha" moments for the composition while looking at this again, however, the lever rule concept still escapes me

7. Mar 26, 2015

### Staff: Mentor

http://en.wikipedia.org/wiki/Lever_rule