Diffusion in material You are hardening a very thick tool plate made of BCC Fe by...

Diffusion in material

You are hardening a very thick tool plate made of BCC Fe by increasing the carbon concentration in its surface layer by heating the tool in the presence of a C-rich gas (e.g. methane) which maintains a constant C concentration at the surface. A heat treatment at 600 °C for 100 minutes results in a C concentration of 0.75 wt% at a position 0.5 mm below the surface. How long would it take to obtain the same result (i.e. the same C concentration at the same depth) if the heat treatment were conducted at 900 °C. Schematically draw the C concentration profile (i.e. the C composition as a function of the distance from the surface) in the tool plate. At either of the temperatures, does the diffusion rate (measured by the diffusion flux) go up or down with increasing distance from the surface and why?

D₀ = 2 x 10^-6 m²/s and Q_d = 84 kJ/mol

Expert Solution

samet mamat answered 2 years ago

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