Slip Systems (FCC, BCC, HCP)

UC Berkeley
MSE 113
Office Hours

[@rintughosh2978]

Sir in bcc no of slip system is 48 or 24

[@Godjunpyo]

Dear Rintu, Thanks for your kind clarification. You are absolutely right. The total number of slip systems in bcc materials can be up to 48. There are 12 slip systems on {110} plane. Additionally, there are 36 systems more: 24 on {123} and 12 {112}. As you see in my note, the 12 slip systems are on {110} plane. But I think my summary might mislead some people. The purpose of this lecture is to help students easily understand the slip directions with a vector concept. That is why I tried teaching with a specific plane {110}. I will pin your comment so that many people can understand without any misunderstanding. Again, I appreciate your kind comments. Many thanks!

[@cdvinoth1]

Thanks for the beautiful explanation. What about the primitive simple cubic unit cell.. There wont be any slip planes (as atoms are only in corners and so no face is packed) and hence no directions or ?

[@Eng.Katos_Koech01]

Very helpful. I now can denote slip planes and directions and determine the number of slip sysstems.

[@Godjunpyo]

Glad that my lecture helps. Please read a textbook as well for more details and for your better understanding. Hope you can find more useful knowledge in my channel. Good luck!

[@billy1104]

This video is really helpful, but I have a question. According to the book "Manufacturing Engineering and Technology, Seventh Edition" written by Serope Kalpajian and Steven R. Schmid , There are 48 slip systems in BCC. I want to know why is that?? (page. 43)

[@fakeidofathug9859]

If a sqaure plane is drawn in fcc joining four corners containing body diagonals. Will it be a slip system

[@Nina-ry4kx]

life saver, thank you so much !!

[@Godjunpyo]

I am glad that my video helps you. Cheers!

[@JK-ku8fe]

안녕하세요! 그 Ans 할때 혹시 처럼 숫자의 위치를 변화시켜서 쓰면 안되는건가요? 무조건 이라고 써야하는건가요?

[@Qfu005]

how do you get the FCC firection in when you have 6 different slip direction

[@rajughimire6003]

Great explanation..Keep it up

[@Godjunpyo]

Thanks for watching!

[@sigietharyopranoto7312]

is the slip plane for HCP (001) or (0001) ?

[@utkuakyuz2040]

Great explanation thank you !!

[@Godjunpyo]

Thanks for watching!

[@podemsahithnitap1840]

thank you sir for explaining this concept

[@Godjunpyo]

I am glad that you enjoyed this video.

[@melcoriumleatherart]

Hi, great explanation, i still have problems with the index of BCC planes... what are the index for the violet plane, the one perpendicular to the first one you drew... i think they could be {010} but I'm not sure. Could you please write down all of them as you did for FCC.. so i can check my results. Thank you

[@melcoriumleatherart]

I have this exercise and i don't know how to solve it... : for a unit cell BCC determine the miller indices of the planes belonging to the family of sliding planes {110} which include the sliding direction [111] and draw them in the unit cell

[@karishmasharma4176]

Well explained...

[@mmokhtabad]

it is a nice videos (with 2X playback speed :) )

[@dinnizayn439]

thank you

[@Godjunpyo]

You're welcome. Good luck!

[@user-vy1mc8fh3h]

형님 감사합니다 msde 학부생인데 교수님보다 형님이 영어로 설명해주시는게 더 잘들어오네요 ㅎㅎ 그런데 한 가지 궁금한게 BCC의 경우 제가 배우기론 48가지 slip systems를 가진다고 하던데 이건 어떻게 이해할 수 있을까요?

[@Godjunpyo]

아마 1) alpha-Fe, W, Mo의 경우: {110} 12개 3) alpha-Fe, K의 경우: {321}

[@leovinglee5795]

actually， I want to know the software drawing the cube you used in this video？

[@Godjunpyo]

I am using "Notability" app in iPad.

[@leovinglee5795]

there is another question,sir. How could I know the angle between the loading axis and crystal direction in polycrystal?I've read some paper, they told me using the triangle in stereographic prejection ,but how?

[@iputuwidiantara2919]

@@leovinglee5795 If you know the vector of both loading axis and crystal direction, you can calculate the angle.

[@seunghwanmom6396]

감사합니다 교수님! 혹시 simple cubic은 왜 안 다루는지 알수있을까용?

[@Godjunpyo]

너무 단순한 시스템이라 다루지 않았던 것 같습니다. 보통 학생들로부터 많이 질문을 받는 내용이 위의 3가지 시스템이었기 때문에 강의를 했던 것입니다.

[@seunghwanmom6396]

Sc에서는 slip system을 plane3개와 수직인 direction2개로 6개로 생각했는데 틀린부분이 있나요 교수님? 알려주신다면 감사하겠습니다!

[@cheechenthing8568]

This video is great, but how should i find the planes (like why FCC is triangle, BCC is rectangular...)

[@Godjunpyo]

That is a very nice question. We assume that the slip happens on the close packed planes. In case of FCC and BCC, their close packed planes have to be triangle and rectangular, respectively, considering those planes contain the atoms the most. Thanks for watching the video. Hope you understand well!

[@cheechenthing8568]

@@Godjunpyo thank you very much

[@iputuwidiantara2919]

Actually, if you extend the atoms, you will see that all planes are rectangular. In the video, it seems to be triangle because the lecturer explain the plane in one unit cell

[@user-nt1ew9kw4f]

謝謝你 我終於知道最密堆積面數量怎麼算了

[@Godjunpyo]

You are welcome. You can go to my website (Godjunpyo.com) and find some pdf files or other lectures. Enjoy!

[@khalighian]

Thanks, I name the name of app that you are using for drawing the slip systems and you are writing on it please.

[@Godjunpyo]

I am using Notability app in iPad. Good luck!

[@khalighian]

thanks @@Godjunpyo

[@pokhimchan697]

Treat (0,-1,1) and (0,1,-1) as same direction in FCC slip plane ?

[@pokhimchan697]

if no then there should have 6 direction in 1 plane, doesn't it?

[@Godjunpyo]

Please see the answer below prepared by Godjunpyo AI. In an FCC (Face-Centered Cubic) crystal structure, the slip planes are the {111} family of planes, and the slip directions are along the family of directions. The slip systems in an FCC crystal are represented as {111}. Now, to address your question: (0,-1,1) and (0,1,-1) are not considered the same direction in the FCC slip plane. They are, in fact, opposite directions. The negative sign indicates the direction is opposite to the positive one. In the (111) slip plane, there are three distinct slip directions: 1. [1̅10] 2. [01̅1] 3. [1̅01] The lines above the numbers indicate a negative direction. These three directions are not parallel to each other and are separated by an angle of 60° within the slip plane. Each of these directions has an opposite direction: 1. [110] 2. [011] 3. [101] So, in total, there are six distinct directions within a single {111} slip plane. The opposite directions are not considered as separate slip directions because the slip can occur in both positive and negative directions along the same line. Therefore, you are correct in stating that there are six distinct directions within a single slip plane in an FCC crystal structure, but they are counted as three pairs of opposite directions, not six independent directions.

[@goms2939]

What app you use here?

[@Godjunpyo]

Notability with iPad

[@dennispop3223]

Soooo......plane (111).....contains 6 directions???right????...the directions are [-110] [1-10] [01-1] [0-11] [10-1] and [-101]......or am i wrong???

[@Sid1699]

plane (111) contains 6 directions but only 3 of them are slip directions as [-1 1 0] and [1 -1 0] are parallel and considered as only 1 slip direction and so on...

[@phivosaslanis2608]

In BCC you lost me. First of all you show only the {110} and not the {211} and the {321}. Secondly, when you do show {110}, you draw 5 planes in total from which 2 are coupled with the 2 others (yellow and light blue are same to purple and pink because they are parallel o each other) and the last one, the light blue is wrong. It doesnt exist in reality of {110} because in doesnt include the center atom, hence it is not high atom density plane. (I am refering to 20:55 drawing.)

[@Godjunpyo]

Hi Phivos, Thanks for your kind reply. I think there are some issues when I explained the BCC structure. As mentioned earlier, the main purpose of this lecture is to explain the vectors on the slip planes easily to students. I think I should definitely prepare another video to thoroughly go through the background and theory later. Thanks for your kind understanding and corrections. I will work hard to provide better contents to help students.