An FCC iron-carbon alloy initially containing 0.55 wt% C is exposed to an oxygenrich and virtually carbon-free atmosphere at 1325 K (1025 ºC). Under these circumstances the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere; that is, the carbon concentration at the surface position is maintained essentially at 0 wt% C (This process of carbon depletion is termed decarburization.) At what position will the carbon concentration b