3. (i). (3 points) Which of the diffusion is faster, interstitial diffusion or vacancy diffusion? And Why? (ii) (4 points) Which one has the greatest magnitudes of the diffusion coefficients:

(A)N in Fe at 600 K (B) Cr in Fe at 600 K (C)N in Fe at 900 K (D)Cr in Fe at 900 K And justify your choice. (iii) (10 points) The diffusion coefficients for iron in nickel are given at two temperatures: (а)Determine the values of Do and the activation energy Qa. (b)What is the magnitude of D at 1100°C (1373 K)?