Diffusion Flashcards
Mass transport by atomic motion
Diffusion
In an alloy, atoms tend to migrate from regions of high concentration to regions of low concentration
Interdiffusion
In an elemental solid, atoms also mirate
Self-diffusion
Atoms exchange with vacancies
Vacancy diffusion
Simulation of interdiffusion across an interface
Diffusion Simulation
Diffuse carbon atoms into the host iron atoms at the surface
Case Hardening
The presence of what element makes iron (steel) harder
Carbon
formed by joining bars of two different metals together so that there is an intimate contact between the two faces
Diffusion Couple
Process where atoms of one metal diffuse into another
Interdiffusion
Another term of interdiffusion
Impurity Diffusion
Diffusion for pure metals, where atoms are exchanging positions of the same type
Self-Diffusion
Involves the interchange of an atom from a normal lattice position to an adjacent vacant lattice site
Vacancy Diffusion
Involves atoms that migrate from an interstitial position to a neighboring one that is emptty
Interstitial Diffusion
Rate of mass transfer
Diffusion Flux
Formula for diffusion flux
J = M/At
mass/area*time
Occurs when the diffusion flux does not change with time
Steady-State Diffusion
Resulting curve when concentration is plotted against position
Concentration ProfileT
The slope at a particular point on the concentration profile is called the
concentration gradient
constant of proportionality in diffusion
Diffusion coefficient
used in the context of what compels a reaction to occur
Driving Force
Most practical diffusion sitautions
Nonsteady-state diffusion
What law is used in nonsteady-state diffusion
Fick’s Second Law
