How the ductility of metal change when grains is decreased ?

[QuyetThangTr]

How the ductility of metal change when grains is decreased ?

Hello every body, I'm from Vietnam. I have a question that : if we decrease the size of the grain of metal by heat treatment, what happen to the ductility of that metal, increase or decrease, and why ? for example, the metal of plain steel.
P/S: It's the first time I post my question, if I make any mistake, please forgive to me, hi

 

[vincent_vega]

If the grain size is larger the material is less brittle so the ductility is higher

 

[pukb]

If the grain size decreases, there is greater resistance for the motion of dislocations due to increased grain boundary area and frequent change in orientation of slip planes due to misorientation of grains.Hence a larger stress would be required to move dislocations. This would imply that the strength of material has increased.
It is calculated using hall petch equation.

 

[iftikhar]

Dear Sir, Kindly send me the proper referance of the following statement)
If the grain size decreases, there is greater resistance for the motion of dislocations due to increased grain boundary area and frequent change in orientation of slip planes due to misorientation of grains.Hence a larger stress would be required to move dislocations. This would imply that the strength of material has increased.
It is calculated using hall petch equation.

 

[pukb]

You can go through the book on Material science basics by Callister.
Read dislocations section.
I am sorry, i do not remember full name of the book

 

[iftikhar]

hi i am from pakistan. i want to make thin film of Mg doped AlSb. when 25% magnasium (Mg) is doped in AlSb I saw rods instead of grain size from SEM (Scanning Electron microscope) graph. can anybody tell me this reason with referance.
thanks

 

[iftikhar]

hi i am from pakistan. i want to make thin film of Mg doped AlSb. when 25% magnasium (Mg) is doped in AlSb I saw rods instead of grain size from SEM (Scanning Electron microscope) graph. can anybody tell me this reason with referance.
thanks