1. Describe in words what is carburization of steel ? Which Fick's law (the first or the second law) should be employed to study the carburization process ? Which equation should be used to estimate the time and position dependent carbon concentration?

2. Describe the materials setup and the corresponding equation that can be used to determine the self-diffusion coefficient of gold.

3. Prove by differentiation that the following equation is a solution of Fick's second law ; Explain the meaning of relaxation time and why short wavelength variations of composition die quickly.

C=C+Bosinexp with relaxation time? 12 T = DB