Study of cementite and ferrite interface by AFM

Abstract

Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of alpha-ferrite (88 wt%) and cementite (12%) that occurs in some steels and cast irons. It forms by a eutectoid reaction as austenite is slowly cooled below 723°C. Diffusion, is a spontaneous process in which there is movement of particles from an area of high concentration to an area of lower concentration until equilibrium is reached.When steel cools from higher temp. to lower temp. below eutectoid temp. it forms pearlite and ferrite .Pearlite is a two phase lamellar structure of layers of ferrite and cementite ferrite has lesser carbon content than austenite so remaining carbon diffuse towards cementite so it forms a diffused zone across the interphase.