Why does the eutectic lamellar structure form the way it does?

The lamellar eutectic structure produces the characteristic zebra stripes. The reason this microstructure results is because the liquid must split into two different solids with different compositions at a single temperature. Since the transitions happens quickly and diffusion lengths are limited due to the lower temperature, the atoms can't move far and we end up with thin stripes of the two solids.

[@mikethechemis]

It seems that your channel appears in search results every time I look for good explanation to some phenomenon. It would be a great pleasure to have you as a teacher. Thanks to RUclips and to your efforts it's possible in some degree.
Many thanks!

[@TaylorSparks]

Oh wow, you don't know how happy that makes me to hear feedback like this. Glad it could be helpful.

[@FearNoSteel]

Great explanation, I was always curious from looking at the diagram on pearlite formation but these never explained why in the text.

[@mjs1592]

Very helpful, thanks

[@TheMachinist97]

At the eutectic point, does the enthalpy of mixing have to be positive?