Dislocation Systems (The Class dislocationSystem)

This section describes the class dislocationSystem.

On this page ...
Class Description
Edge Dislocations
Screw Dislocations
Slip Systems
Dominant Dislocation Systems
The Dislocation Tensor
Complete Function list

Class Description

Dislocation are microscopic displacements within the regular atom lattice of a crystaline material ussualy as a result of plastic deformation. Dislocations are described by a Burgers vector describing the direction of the atomic shift and a line vector describing the direction of the displacements within the material. One distinguishes two cases:

Edge Dislocations

Here the directions of the atomic shifts are orthogonal to the direction the displacements spread within the material. In order to define a edge dislocation we proceed as follows

% define a crystal symmetry
cs = crystalSymmetry('432');

% define a burgers vector in crystal coordinates
b = Miller(1,1,0,cs,'uvw')

% define a line vector in crystal coordinates
l = Miller(1,-1,-2,cs,'uvw')

% setup the dislocation system
dS = dislocationSystem(b,l)
 
b = Miller  
 size: 1 x 1
 symmetry: 432
  u 1
  v 1
  w 0
 
l = Miller  
 size: 1 x 1
 symmetry: 432
  u  1
  v -1
  w -2
 
dS = dislocationSystem  
 symmetry: 432
 edge dislocations : 1 x 1
 Burgers vector  line vector  energy
      [1  1  0]    [1 -1 -2]       1
 

Screw Dislocations

Screw dislocations are characterized by the fact that Burgers vector and line vector are perpendicular to each other.

% define a burgers vector in crystal coordinates
b = Miller(1,1,0,cs,'uvw')

% define a line vector in crystal coordinates
l = Miller(1,1,0,cs,'uvw')

% setup the dislocation system
dS = dislocationSystem(b,l)
 
b = Miller  
 size: 1 x 1
 symmetry: 432
  u 1
  v 1
  w 0
 
l = Miller  
 size: 1 x 1
 symmetry: 432
  u 1
  v 1
  w 0
 
dS = dislocationSystem  
 symmetry: 432
 screw dislocations: 1 x 1
 Burgers vector  energy
      [1  1  0]       1
 

Slip Systems

Dislocation systems are tightly related to slip systems. Given a set of slip systems the corresponding dislocation systems can be computed by

% dominant slip systems in cubic fcc material
sS = symmetrise(slipSystem.fcc(cs))

% the corresponding dislocation systems
dS = dislocationSystem(sS)
 
sS = slipSystem  
 symmetry: 432
 size: 24 x 1
   u    v    w  | h    k    l CRSS
   0    1   -1    1    1    1    1
  -1    0    1    1    1    1    1
   1   -1    0    1    1    1    1
   0   -1    1    1    1    1    1
   1    0   -1    1    1    1    1
  -1    1    0    1    1    1    1
   1   -1    0    1    1   -1    1
   1    0    1    1    1   -1    1
   0    1    1    1    1   -1    1
  -1    0   -1    1    1   -1    1
   0   -1   -1    1    1   -1    1
  -1    1    0    1    1   -1    1
   0    1   -1   -1    1    1    1
   1    0    1   -1    1    1    1
   1    1    0   -1    1    1    1
  -1    0   -1   -1    1    1    1
  -1   -1    0   -1    1    1    1
   0   -1    1   -1    1    1    1
  -1    0    1    1   -1    1    1
   1    1    0    1   -1    1    1
   0    1    1    1   -1    1    1
  -1   -1    0    1   -1    1    1
   0   -1   -1    1   -1    1    1
   1    0   -1    1   -1    1    1
Warning: Miller indices are converted to hkl 
 
dS = dislocationSystem  
 symmetry: 432
 edge dislocations : 24 x 1
 Burgers vector  line vector  energy
      [0  1 -1]    (2 -1 -1)       2
     [-1  0  1]   (-1  2 -1)       2
      [1 -1  0]   (-1 -1  2)       2
      [0 -1  1]   (-2  1  1)       2
      [1  0 -1]    (1 -2  1)       2
     [-1  1  0]    (1  1 -2)       2
      [1 -1  0]    (1  1  2)       2
      [1  0  1]   (-1  2  1)       2
      [0  1  1]   (-2  1 -1)       2
     [-1  0 -1]    (1 -2 -1)       2
      [0 -1 -1]    (2 -1  1)       2
     [-1  1  0]   (-1 -1 -2)       2
      [0  1 -1]    (2  1  1)       2
      [1  0  1]   (-1 -2  1)       2
      [1  1  0]    (1 -1  2)       2
     [-1  0 -1]    (1  2 -1)       2
     [-1 -1  0]   (-1  1 -2)       2
      [0 -1  1]   (-2 -1 -1)       2
     [-1  0  1]    (1  2  1)       2
      [1  1  0]    (1 -1 -2)       2
      [0  1  1]    (2  1 -1)       2
     [-1 -1  0]   (-1  1  2)       2
      [0 -1 -1]   (-2 -1  1)       2
      [1  0 -1]   (-1 -2 -1)       2
 
 screw dislocations: 6 x 1
 Burgers vector  energy
      (0 -1 -1)       1
      (0 -1  1)       1
     (-1  1  0)       1
      (1  0  1)       1
      (1  1  0)       1
      (1  0 -1)       1
 

Dominant Dislocation Systems

dS = dislocationSystem.bcc(cs)
Warning: Miller indices are converted to hkl 
 
dS = dislocationSystem  
 symmetry: 432
 edge dislocations : 48 x 1
 Burgers vector  line vector  energy
      [1 -1  1]   (-2 -1  1)       2
      [1  1 -1]    (2 -1  1)       2
      [1  1 -1]    (1 -2 -1)       2
     [-1  1  1]    (1  2 -1)       2
      [1 -1  1]   (-1  1  2)       2
     [-1  1  1]   (-1  1 -2)       2
      [1 -1  1]    (1  2  1)       2
      [1  1  1]   (-1  2 -1)       2
      [1  1 -1]    (1  1  2)       2
      [1  1  1]   (-1 -1  2)       2
     [-1  1  1]    (2  1  1)       2
      [1  1  1]    (2 -1 -1)       2
     [-1  1  1]    (0  1 -1)       2
      [1 -1  1]   (-1  0  1)       2
      [1  1 -1]    (1 -1  0)       2
     [-1  1  1]   (-1  0 -1)       2
      [1 -1  1]   (-1 -1  0)       2
      [1  1 -1]    (0 -1 -1)       2
      [1  1 -1]    (1  0  1)       2
     [-1  1  1]    (1  1  0)       2
      [1 -1  1]    (0  1  1)       2
     [-1 -1 -1]    (0 -1  1)       2
     [-1 -1 -1]    (1  0 -1)       2
     [-1 -1 -1]   (-1  1  0)       2
     [-1  1  1]   (-1  4 -5)       2
      [1 -1  1]   (-5 -1  4)       2
      [1  1 -1]    (4 -5 -1)       2
     [-1  1  1]   (-4  1 -5)       2
      [1 -1  1]   (-5 -4  1)       2
      [1  1 -1]    (1 -5 -4)       2
      [1  1 -1]    (4  1  5)       2
     [-1  1  1]    (5  4  1)       2
      [1 -1  1]    (1  5  4)       2
     [-1 -1 -1]   (-1 -4  5)       2
     [-1 -1 -1]    (5 -1 -4)       2
     [-1 -1 -1]   (-4  5 -1)       2
      [1 -1  1]    (1 -4 -5)       2
      [1  1 -1]   (-5  1 -4)       2
     [-1  1  1]   (-4 -5  1)       2
      [1 -1  1]    (4 -1 -5)       2
      [1  1 -1]   (-5  4 -1)       2
     [-1  1  1]   (-1 -5  4)       2
     [-1 -1 -1]   (-4 -1  5)       2
     [-1 -1 -1]    (5 -4 -1)       2
     [-1 -1 -1]   (-1  5 -4)       2
      [1  1 -1]    (1  4  5)       2
     [-1  1  1]    (5  1  4)       2
      [1 -1  1]    (4  5  1)       2
 
 screw dislocations: 4 x 1
 Burgers vector  energy
     (-1 -1 -1)       1
      (1 -1  1)       1
     (-1  1  1)       1
      (1  1 -1)       1
 

The Dislocation Tensor

As each dislocation corresponds to an deformation of the atom lattice a dislocation can also be described by a deformation matrix. This matrix is the dyadic product between the Burgers vector and the line vector and can be computed by

dS.tensor
 
ans = dislocationDensityTensor  
  size   : 52 x 1   
  unit   : au       
  rank   : 2 (3 x 3)
  mineral: 432      

The unit of the deformation tensor is the unit of the burgers vector which is assumet to be au in MTEX.

Complete Function list

Syntax
dS = dislocationSystem(b,l)
dS = dislocationSystem(sS)
Input
b@Miller Burgers vector
n@Miller line vector
sS@slipSystem
prpoisson ratio