1. Formation of Pearlite: Pearlite forms through a "eutectoid" reaction at $727^{\circ}\text{C}$ and $0.76\%$ carbon. When austenite ($\gamma$-iron) is cooled slowly below this critical temperature, it transforms into a layered (lamellar) structure.
2. The Two Components: Pearlite is a mechanical mixture consisting of alternating layers of two distinct phases:
• Ferrite ($\alpha$-iron): A relatively soft, ductile phase with very low carbon solubility.
• Cementite ($Fe_3C$): An extremely hard and brittle iron carbide compound.
3. Why the Name "Pearlite"?: Under a microscope, the alternating thin layers of these two phases cause light to diffract, creating an iridescent appearance similar to "Mother of Pearl," which gives the structure its name.