49. Dislocations Intersections Jogs and Kinks

Basics of Mechanical Behavior of Materials
This video deals with
1. What are breaks on dislocation lines?
2. What are jogs and kinks?
3. Dislocations intersection to form Jogs and Kinks?
4. Movement of jogs
Addendum: @10:59, I made an error when I said the b1 screw dislocation slides downward; it actually moves in the opposite direction as the b2 screw dislocation. However, the remaining portions of the explanation are not impacted by this error, thus that is the only fix. FYI, dislocation always moves in the direction perpendicular to its tangent vector (irrespective of nature).

[@sixy5195]

It was great, thanks for the clear explanation

[@nigel3436]

tks i got it easily with ur lecture

[@Dzevad75]

The presence of the Peierls barrier causes dislocations to tend to lie in low index directions at low temperatures.
Where the dislocation locally leaves this direction a kink (in the glide plane) or jog is formed. These core defects can
occur by geometric necessity, at thermal equilibrium, or by dislocation intersection.They can serve as charged defects
in ionic crystals,important as extrinsic sources of charged point defects and of electronic defects.
Kink concepts were used to describe low-temperature deformation (creep and internal friction) by double-kink nucleation and growth. Interestingly, these models have been found to give kinetic equations that also apply to the recently developed theory for soliton motion in
one dimensional conductors and to crystal growth by ledge motion. Jogs are important as sites where dislocation climb occurs, the jogs acting as sites for local equilibration of vacancies (interstitials).

[@nirajchawake]

Thank you for your thoughtful and comprehensive comment. One of the best inputs I've ever received.

[@neerajdhandia7876]

Hi,
Thank you for great lectures!!
@10:59 you mention that b1 screw dislocation moves down, which is along the direction of burger vector and dislocation line. But we know that screw dislocation always moves perpendicular to the burger vector/dislocation line.

[@nirajchawake]

Hi Neeraj
Many thanks for pointing this.
@10:59, I made an error when I said the b1 screw dislocation slides downward; it actually moves in the opposite direction as the b2 screw dislocation. However, the remaining portions of the explanation are not impacted by this error, thus that is the only fix. FYI, dislocation always moves in the direction perpendicular to its tangent vector (irrespective of nature). I have added an addendum to the video.

[@sktechnologyandmaterialsci8774]

Such a nice explanation

[@nirajchawake]

Thanks for your kind words. Glad to know that it is useful.

[@ankitprasad5382]

Bhaiya tell us something more about motion of kinked and joged dislocation:conservative and non-conservative

[@mianimran5985]

good explanation...

[@nirajchawake]

Thanks. Glad to know that it is useful.

[@soumyadeeppradhan]

@20:00 is t1 and b1 parallel or perpendicular?

[@nirajchawake]

It's a kink, so t1 || b1

[@dabarmanashu8376]

​@@nirajchawakesir but t1 is perpendicular to b1,sir see it once,because in deiter it is given

[@shaymarom3222]

@@nirajchawake i agree with soumy, they are perpendicular to each other, not parallel. and baxed on that you determine if it is a jog or kink

[@nirajchawake]

You are right. There is an error while explaining it.

[@soumyadeeppradhan]

@@nirajchawake thank you sir for the clarification