In this lesson, we're going to review some of the concepts that we've been discussing so far with respect to the isomorphous diagram. First of all, we have a region where we have single phase and we have a solid phase. We had that region that's separating the single phase liquid and the single phase solid and that two phase range and we describe the boundary that separates the single phase liquid from that two-phase region. And we refer to that boundary as the liquidous boundary. Over here we now have the solidus boundary. And the solidus boundary winds up separating the single phase field, the solid, from the liquid plus solid phase field. Now, again, what we can do is, we can use some values with respect to compositions and temperatures so that we can actually see how all of these ideas come into play in calculating our compositions and phases as we go through the two phase field. Now, I'm doing a number of these and presenting a number of pieces of data for you to analyze. Just because even though this is a simple phase diagram, when we get into more complex phase diagrams and binary systems we're going to do essentially the same analysis when we get into a two phase field so this gives us a little bit of heads up when the diagrams become progressively more complex as we move through this particular module. So, here are our datasets where we have the temperature. I'm going through here and we're putting in the composition. At that first temperature we have a composition for the solid and the liquid. When we look at the fraction of solid we have, it is essentially zero. We have a little bit of solid phase, not much at that temperature. The majority of it's going to be the liquid phase which is the composition of our alloy. And now as we go down in temperature, we're seeing a shift, or an increase in the amount of solid we have. That is, our line is moving closer to the solid phase boundary, at that given temperature, we drop down in temperature again, and we can see that we are increasing the amount of solid that we have. And as we go further down in temperature. We are increasing that amount of solid and decreasing the fraction of liquid. Remember that fraction of liquid is going to be that difference between the composition of the liquid minus the composition of the alloy divided by that distance that goes from the solid phase to the liquid phase. And now, as we come through the structure or come through this two phase field, what's happening now is we have a solid whose composition is effectively the composition of the alloy and what's given over on the left. Is the composition of that liquid that is the last thing to be present in terms of the liquid phase, and we drop down in temperature. Below that isotherm, we'll find that all the liquid is gone and we have 100% solid. And so that's the compositions of our solids as we go down through that two phase field. Now, what we can do is we can take the data from this particular set and knowing the compositions at each one of the temperatures, the composition of our alloy, we can then go through and calculate the fractions of those phases. And what I've done to make the calculation at T2 and at that particular temperature we see at temperature T2 that we have a little bit of solid that's forming about 37%. And the remaining phase that's present is the liquid phase. We go down in temperature, at now the temperature T3, we're seeing more solid phase and less liquid phase and eventually now when we get down to temperature T4 we're seeing only about 30% liquid, and the remaining of that is now solid. So, you should go through and go through the calculations and make sure that you really understand how to use the lever rule. And make these calculations, because as we get into more complicated diagrams. Once you understand this, you will be able to go through the same process in these complicated systems. Thank you.