If a slab of carbon is placed on a clean surface of iron at a high temperature, the carbon will diffuse into the iron. After a short time the profile of the carbon concentration versus length of diffusion into the iron looks like: Iron Carbon Surface Concentration of Carbon in Iron O 0% C 0 mm Distance from surface Concentration of Carbon in Iron O 0% C 0 mm Distance from surface Concentration of Carbon in IronO 0% C O mm Distance from surface