|
A
unit dislocation is a one dimensional lattice defect in a crystal characterized
by a Burgers vector, b, that is a unit translation vector of the
lattice. The Burgers vector has a constant magnitude and direction for
a given dislocation. The line of the dislocation is characterized by a
line vector, t, that points along the local direction of the defect.
An
edge dislocation has its Burgers vector normal to its line vector. A screw
dislocation has its Burgers vector parallel to its line vector. A mixed
dislocation has its Burgers vector at an arbitrary orientation with respect
to the line vector.
The
energy per unit length of a dislocation is proportional to the shear modulus,
G, of the lattice and the square of the Burgers vector:
Energy per Unit Length = Gb2
a
fact that favors dislocations that have the shortest possible Burgers vectors. |
|
