Question

A thin plate of a binary alloy of composition N_A1 = 0.245 and N_B1 = 0.755 was welded to a similar plate of composition N_A2 = 0.255 and N_B2 = 0.745 so as to form a diffusion couple. After a diffusion anneal for 150 hours at 1300 K, the composition at a plane 2 x 10^-4 m from the original weld interface, on the side whose starting composition was N_A = 0.245, was observed to be N_A = 0.248. Determine the diffusion coefficient.

Answer 1