 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Plastic
Deformation |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Frank-Reed
Source
· Observations
show that new dislocations are created to permit plastic
deformation.
· The
observed shear displacements require about 1000 active dislocations on
a single slip plane. A source of these dislocations that can emit dislocation
loops on a single slip plane is needed.
· Frank
and Reed proposed a dislocation source that is illustrated below for an
isotropic material. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
·
The
straight segment (a) bows into a loop due to the external forces. This
closes on itself, creating a free loop (g) and a new segment that can repeat
the process. |
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
From:
Barrett, Nix, and Tetelman, "The Principles of Engineering Materials,"
Prentice Hall (1973) |
|
|
|
|
|
|
|
|
|