answer 5.6

answers: The compositions at 780oC are: -phase, 0.09 mol. % C; -phase, 2.1 mol. % C and 3.3 mol. % C. Answer: thickness of -phase and -phase are 0.882 mm and 0.118 mm, respectively.

5.6 This problem is concerned with steady state diffusion in an iron-carbon alloy. The pertinent portion of the FeC phase diagram is shown. A sheet of iron 1mm thick is treated at 780C so that one face is maintained at 3.3 atom \% carbon and the other face is at zero carbon. Plot the steady state carbon content of the iron as a function of distance through the sheet. Indicate compositions and distances of important points. For the purpose of this problem, the diffusion coefficients at 780C are as follows: Forferrite()Foraustenite()D=2.5106cm2/sD=2.5108cm2/s