Question

Compute diffusion coefficients for the interdiffusion of carbon in both (a) α-iron (BCC) and (b) γ-iron (FCC) at 800.˚C. Assume that D0 for the interdiffusion of carbon in α-iron and in γ-iron are 1.10 × 10-6 and 2.30 × 10-5 m2/s, respectively, and that Qd are 80.0 and 148 kJ/mol, respectively.

Answer 1

Answer:

a)1.404 E-10 m^2/s

b)1.438 E-12 m^2/s

Explanation:

Diffusion Coefficients can be calculated at different temperatures taking into account the energy of the diffusive process, remember that this process takes place in the interstices of the solid, and gets with higher temperatures due to the higher kinetic energy of the particles.

$D=D_{o} *exp(-Q/RT)$

a) For α-iron (BCC)

$D=1.10*10^{-6} m^{2}/s *exp(-80.0kJ/mol/8.314*10^{-3}kJ/mol*k*1073.15K)= 1.404*10^{-10} m^{2}/s$

b) For γ-iron (FCC)

$D=2.30*10^{-5} m^{2}/s *exp(-148.0kJ/mol/8.314*10^{-3}kJ/mol*k*1073.15K)= 1.438*10^{-12} m^{2}/s$