Question

The diffusion coefficients for carbon in nickel are given at two temperatures are as follows:

At T= 600°C, D=5.5 × 10^–14 m²/s

At T= 700°C, D=3.9 × 10^–13 m²/s

(a) Determine the values of D₀ and Q_d.

(b) What is the magnitude of D at 850°C?

Answer 1

The diffusion rates at any temperature is given by the equation,

.........................................(1)

From the given data,

and

Re-arrange the above equations. Then

.................................................(2)

a)

Thus from (1),

.................................................(3)

(b)

(c)

From (1) and (3),

Thus at 850⁰C, the magnitude of D is