An fcc iron–carbon alloy initially containing 0.35 wt% c is exposed to an oxygen-rich and virtually carbon-free atmosphere at 1400 k (1127°c). 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 be 0.15 wt% after a 10-h treatment? the value of d at 1400 k is 6.9 x 10-11 m2 /s.