1. A 1080 type of steel is exposed to an oxygen-rich and virtually carbon-free atmosphere at 3 different temperatures of 700, 800 and 1000C separately. 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.) a) Sketch the time series composition profiles at times to, ti, tz and te for all temperatures separately. Clearly indicate all critical compositions referring to a schematic phase diagram. b) Below each composition profile of each temperature sketch the time series chemical potential profiles at same times to, tu, tz and to. c) Calculate the carbon composition at a distance 16.5 mm from the external surface of the steel, where carbon composition is exactly O wt%, after a 12 h treatment at 700 C. d) At what depth from the external surface of the steel, where carbon composition is exactly O wt%, will the composition you have calculated in part c) be observed after a 12 h treatment at 1000 C e) How many millimeters will be the approximate practically measurable total decarburization depth for both of these cases from the surface up to the point where deviation from initial composition starts? Solvent Solute D. (cm/s) Q (cal/mole) 29 300 a-Fe 2.20 7-Fe 32 000 0.12