Diffusion Paths

Lattice Diffusion
Surface Diffusion
Grain Boundary Diffusion

[@jonathangarcia2757]

I found this very informative, very clear and well explained. Thank you so much for posting this.

[@siddharthjena2189]

Sir What is the Activation energy required for Pipe diffusion in comparison other three diffusions?

[@rajeshprasad101]

Well, let me just make an intuitive guess. As pipe has only one-dimensional freedom whereas lattice has zero and surface 2-dimensional activation energy of pipe diffusion should be higher than that of surface diffusion and less than that of lattice diffusion. With respect to the grain boundary, it may be comparable. But these are just my guess, we should check some data.

[@akashmodi1403]

Sir I have a doubt. can we call climb motion of dislocation as diffusion path?

[@rajeshprasadlectures]

Climb motion is not called diffusion path. The climb motion does involve diffusion but the diffusing species either move away or towards the dislocation. The direction of diffusion in not in the direction of motion of dislocation. However, if diffusing species move along the dislocation core then the dislocation does serve as a path of diffusion. It is called pipe diffusion. But in this case, the dislocation itself is stationary and not climbing. This case is not covered in this video.

[@keithtong280]

Dear Sir, May i ask that, what is the diffusion between surface and lattice? what is the diffusion between grain boundary and lattice? Thank you. Best regards Keith

[@rajeshprasad101]

If the diffusion happens through the crystal by interstitial or substitutional mechanism it is called lattice diffusion. In atoms diffuse on the external free surface of the crystal it is called surface diffusion. If the diffusing atom moves along the grain boundary between two crystals it is called grain boundary diffusion.

[@KuldeepSharma-pk6li]

@@rajeshprasad101 Sir, Is activation energy required for pipe diffusion is greater than activation energy required for surface and gb??

[@TimeEnergyConsciousness]

Yes​@@KuldeepSharma-pk6li

[@BC-yr6eg]

👍👍👍

[@tarahman7]

Thank you so much sir

[@sakethvarmakopperla9939]

hi there