In this lecture, we're going to discuss how to determine and draw the microstructure associated with the eutectic alloy upon cooling. And also we'll discuss how this microstructure comes to be, based on cooperative growth mechanism. As we said in the previous lecture, we utilized the phase diagram to predict the microstructure, hence predict the properties. And we utilize the phase diagram to help predict the properties, it helps us to design material systems for some application. Okay. So we're going to look at a hypoeutectic alloy, okay? And this one is going to be 40 weight percent. So if I know it's hypoeutectoid, the composition is less than that of the eutectic, and eutectic composition is 62 weight percent. Okay, so that we are indeed looking at high hypoeutectic alloy at 150 degrees. Again we define our state point then we draw an isotherm that gives us the overall composition, okay? And then If we want the weight fraction, we look at alpha, I take the opposite, leave her here. I get, In this particular case, 99- 40. And then the overall length, 99- 11, I get 67 weight percent. Do a similar manner for beta, okay? Beta, I'm going to take the opposite. Oops. Okay, so again, 40- 11, 29 / 88. The sum does equal 1, so it checks out. So, now let's look at the micro structure. Okay, so now we have the eutectic composition at some temperature above the eutectic temperature. So we know in this case, there's our eutectic temperature. So we're here, so we're going to be all liquid. It's all the same phase, so typically liquids, we just denote by a solid color or even just liquid, okay? Now, when we go through, we're going to cool down and go through the eutectoid isotherm, hence all the liquid will undergo the eutectic reaction. Now, eutectic reaction results in this layered micro structure. So just above the eutectic isotherm, it's all liquid. When we cool below the isotherm or hence the eutectic isotherm, all the liquid is no longer in thermal equilibrium, it must convert to alpha plus beta. And it forms this lamina-type structure where we're going to have beta and alpha. Okay, now you can see the micro structure here, similarly layer light structure. One phase, we'll say alpha is the light, and we'll let beta be the dark. Okay, well here, they got it the opposite, they got beta is the light and alpha. Okay, doesn't matter. But notice above, all liquid and then below I have this lamina-type structure.