Now, if we look at the diagram to the right, the only difference with respect to
the diagram on the left and the one on the right is that we are assuming that
the intermetallic phase that is in the middle of the diagram that we refer to
as beta that we're going to refer to a line compound.
That is, you're not allowed in this particular system any solubility
off the fixed ratio of AB.
Now suppose I pose this question, if you were going to make an alloy
of either the material of the beta phase or
the material of the AB and
you wanted to make sure that the material that you were looking at.
Was something that you could do reproduceably.
One of the big issues with respect to melting large quantities of material is to
make sure that the compositions are each timed the same value.
If we look at the composition on the right.
One of the problems we have is that if we are slightly off
the AB compound, that is either to the left or to the right, what's going to
happen is there will be a melting reaction that occurs at a much lower temperature.
So for example if we happen to have too much B as opposed to the AB, then
we're going to get the utectic reaction in which we begin to form liquid at a lower
temperature than we would if we talk about the AB compound that congruently melts.
And similarly, just to the left, where we have A plus the compound AB.
If we look to the right,
however, on the diagram to the right where we have some solubility
what that allows us to be slightly off our composition by a small amount.
But at the same time we're in a single phase field and we're not going to
experience melting at the temperatures given by two lower Eutectics.
Now one of the reasons that in bring this up is, this particular phase diagram
is very similar, to the types of diagrams where we were looking for
materials that are high melting temperature.
The types of materials that we might use, for example,
in nickel based super alloys where we like to go to higher and higher temperatures.
When you look at the diagram, what is particularly important is the fact that
the compound B melts at a much higher temperature
than either do pure component A or pure component B.
So there would be an advantage of looking at a particular system of the beta phase.