Dislocations and Plastic Deformation

Organized by textbook: learncheme.com/
Explains the concepts of dislocations in metal crystal structures and plastic deformation. Made by faculty at the University of Colorado Boulder Department of Chemical and Biological Engineering.
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[@rebeccamclaren97]

Extremely well explained, thank you so much! My lecturer spent 4 hours trying to cover Cold Working and the effects on grain structure/the crystalline structure, and we all left scratching our heads! It's actually a lot more simple than it was made out to be 😂

[@baotrambelle]

great lecture, professor!

[@marytran5342]

you have a nice voice.

[@gabrielgomes1618]

This is so clear for me now. Amazing video.

[@BeautifulFreakful]

Really well explained

[@adaliangirlinitaly6107]

Well explained! Thank you!

[@soniaamirsoniaamir]

Piling up of these dislocations and slip systems give the materials more strength and hardness

[@criclal1787]

Great Explanation👌🙏

[@karind7513]

1:04 That's not a "missing atom". That's the end of an extra half-plane, or, if you want, a missing half-plane. A missing atom would be a vacancy.

[@alexfabio9]

very helpful

[@aazaanaftab8381]

Superb Video !

[@wukf1]

very good !

[@authenticwarrior7877]

thanks a lot...

[@charliestewart885]

what if a materials lattice structure has no missing atoms and is regular. is it no longer a ductile material? is that the defining feature of a ductile material? great vid thanks

[@radolearn]

Yeah, basically, a perfect lattice wouldn't be ductile anymore. So in theory, such material would be 1000x stronger than the real version of it with dislocations

[@nataliaandreas6466]

thank you so much....

[@junyangzhu4215]

Amazing videos, really helped my exam :)

[@kaeshaun4037]

i dedicate my degree to you thankyou so muchhh

[@AmitSharma-ds7dy]

I like it.

[@bilguunganbold6727]

does density increase,decrease or remain the same after the plastic deformation?

[@troyeemitra919]

Increases. It’s called strain hardening

[@averagesoup8432]

sweet voice

[@baymax6412]

赞赞赞赞赞！对于初学者很有用，一下子就理解了！

[@Illogical.]

I think he/she is saying: Help help help help help! useful for beginners, (something about doing something fast? It doesn't make much sense without the second last character.) (I couldn't translate chinese character number 11 and 19) I assume It's: Help! make it useful for beginners, and do it soon! It's a rough translation, and the persom probably doesn't mean it in such a commanding way.

[@Illogical.]

Please do not assume, that people understand chinese.

[@baymax6412]

@@Illogical. I mean :"thumbs up, it's useful for beginners. the video makes learners understand easily"

[@Illogical.]

@@baymax6412 Ok it makes much more sense then. I just misunderstood the first one and I wasn't able to replicate those other two well enough for the website to recognize it, cause I've forgotten the stroke order rules.

[@SuperHeroMG5000]

Please make a video about jog and kink dislocations.

[@weiliu9537]

+Mert Gümüş kinks and jogs are not dislocations, they are two types of steps on dislocation lines. there are two types of dislocations, edge dislocations and screw dislocations.

[@Illogical.]

I might be getting a little off topic and unrealistic here, but what if the material was perfect? So all of the things (I'm not comfortable using the word lattice, because I'm not 100% sure exactly what it means) line up. Would breaking then involve dislocating all of the things at once and kind of shearing it apart. What if a perfect material is bent? Is it like a cube of ball magnets being ripped apart? Is sodium just a mess of particles, that don't line up, and is that why it's so easy to deform? And where can I find the answer to similar questions? I'm in a complicated situation, where I do not go to school, and I don't have access to this kind of knowledge, and I don't know where to find it.

[@thomasbitler8798]

Eventually after enough cold working and deformation, the dislocations cannot move anymore. They will hit a grain boundary or another dislocation and just can't move. When this happens, the material stops plastic deformation and starts to fracture. I assume, in your so called "perfect material" with no dislocations, it would simply start to fracture instead of deforming because there are no dislocations to move. Materials are ductile because of dislocations. After a lot of coldworking and deformation, the strength of the material increases but the ductility decreases. Metals are ductile because they have lots of dislocations. Ceramics have very few dislocations. This is why ceramics don't bend, but simply fracture.

[@wulf3n773]

@@thomasbitler8798 So ceramics and other brittle materials have very little defects resulting in a sudden fracture?

[@HelixClovers]

elaborate? Quote "Assuming material is above recrystallization temperature. We are assuming material is belowe recrystallization temperature."

[@radolearn]

Why does the amount of dislocations increase in cold forming?

[@elyakem1505]

wwwoowww it's so nice

[@LearnChemE]

Can you elaborate please?

[@AlexSmith-ix4oe]

nice

[@mikekramer1041]

So how does dislocation help with strength?

[@ksenagosutumbo3604]

it doesn't help with strength i.e. how much tensile stress it can take it helps with toughness i.e how much energy it can absorb before it breaks

[@strateeg32]

+Ksenagos Utumbo it does help with strength. in the sense that when plastic deformation occurs the yield strength shifts. Ergo it can take more loads before plastic deformation happens again.

[@tanyafaltens5967]

+MIke Kramer High concentrations of dislocations will impede the motion of other dislocations, through their strain-field interactions. While some pairs of dislocations attract and other pairs repel, on average it will take more energy to move a dislocation when there are other dislocations around it than if it is traveling through a perfect material. Impeding dislocation movement is also the basis of other strengthening mechanisms such as precipitation hardening.

[@keenworld2591]

Tanya Faltens good explaination

[@dylantorres2406]

@@tanyafaltens5967 THANK YOU!! why couldn't my textbook just say this???

[@affanahmedkhan7362]

best

[@giridharg104]

Really sweet and nice voice.makes me listen multiple times😍😍

[@captainmcderpyderp]

ENGG1200 4 lyfe

[@nunenaveena9379]

what a comparision ???????????????/

[@shahid4few]

attractive voice

[@pilkin5378]

spoon... ice cream, am I the only one who doesn't understand wtf she is on about...?

[@thomasbitler8798]

if you get a gallon of icecream out of the freezer and don't let it thaw, and try to take a normal spoon and scoop some out, often times the icecream is too frozen and you just bend the spoon because the icecream won't come out.