Plastic Deformation

· The flow stress for various point defects in a series of matrix materials is shown. The linear dependence of the stress on the square root of the point defect concentration supports the above model.
· Because of their attraction to dislocations, certain impurity atoms can form an atmosphere around the dislocation and this will restrict its motion.
· Carbon and nitrogen interstitials in an iron matrix give rise to strongly bound (0.5 eV/atom) atmospheres. Here it is the tetragonal lattice distortion produced by these interstitials that binds the dislocation.

From: Barrett, Nix & Tetelman,
"The Principles of Engineering Materials,"
Prentice Hall (1973)