Chapter 5: Problem 5
(a) Briefly explain the concept of a driving force. (b) What is the driving force for steady-state diffusion?
Chapter 5: Problem 5
(a) Briefly explain the concept of a driving force. (b) What is the driving force for steady-state diffusion?
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Get started for freeThe activation energy for the diffusion of copper in silver is \(193,000 \mathrm{J} /\) mol. Calculate the diffusion coefficient at \(1200 \mathrm{K}\left(927^{\circ} \mathrm{C}\right),\) given that \(D\) at \(1000 \mathrm{K}\left(727^{\circ} \mathrm{C}\right)\) is \(1.0 \times 10^{-14} \mathrm{m}^{2} / \mathrm{s}\).
Briefly explain the concept of steady state as it applies to diffusion.
Self-diffusion involves the motion of atoms that are all of the same type; therefore it is not subject to observation by compositional changes, as with inter-diffusion. Suggest one way in which self-diffusion may be monitored.
For a steel alloy it has been determined that a carburizing heat treatment of 15 h duration will raise the carbon concentration to 0.35 wt \(\%\) at a point \(2.0 \mathrm{mm}\) from the surface. Estimate the time necessary to achieve the same concentration at a 6.0 -mm position for an identical steel and at the same carburizing temperature.
The diffusion coefficients for carbon in nickel are given at two temperatures: $$\begin{array}{cc}\hline T\left(^{\circ} C\right) & D\left(m^{2} / s\right) \\\\\hline 600 & 5.5\times 10^{-14} \\\700 & 3.9 \times 10^{-13}\end{array}$$.(a) Determine the values of \(D_{0}\) and \(Q_{d}\) (b) What is the magnitude of \(D\) at \(850^{\circ} \mathrm{C} ?\)
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