What is the significance of Burgers vector and Frank Read source in dislocation?

Under an applied stress, the dislocation dissociates into two dislocations of type < > a and < > c . (a and b) Both dislocations < > c and < > a are mobile and bow out in their respective glide planes.

How is Frank Reed source related to dislocations?

Frank Reed Source A Frank-Reed source permits the dislocation multiplication required for slip in crystalline solids. The sequence of source operation is shown and results in the shedding of a dislocation loop and regeneration of a dislocation that can repeat the sequence.

What is Frank’s rule?

By Frank’s rule, it is energetically favorable for the screw dislocation to dissociate into two partial dislocations in the fcc crystal, forming a local constriction. The screw dislocation, along with the local constriction, continues to glide in the (111) slip plane.

What is Frank dislocation?

The Frank partial is an edge dislocation and since the Burgers vector is not contained in one of the {111} planes, it cannot glide and move conservatively under the action of an applied stress. Such a dislocation is said to be sessile, unlike the glissile Shockley partial. However, it can move by climb.

Why Frank Read source is important?

In materials science, a Frank–Read source is a mechanism explaining the generation of multiple dislocations in specific well-spaced slip planes in crystals when they are deformed. When a crystal is deformed, in order for slip to occur, dislocations must be generated in the material.

What is the significance of Burger vector?

The Burgers vector is significant in determining the yield strength of a material by affecting solute hardening, precipitation hardening and work hardening. The Burgers vector plays an important role in determining the direction of dislocation line.

What are Frank loops?

The faulted loop (also called Frank loop) is most easily visualized as either insertion or removal of a layer of atoms, creating a corresponding extrinsic or intrinsic stacking fault associated with condensation of a planar monolayer of vacancies and SIAs, respectively.

How does a frank read source work?

A Frank–Read source consists of a dislocation pinned at two points A and B and subjected to a shear stress. The pinned dislocation expands and wraps around repeatedly forming new dislocation loops.

How Burgers vector is important in the movement of dislocations?

In screw dislocations, they are parallel. The Burgers vector is significant in determining the yield strength of a material by affecting solute hardening, precipitation hardening and work hardening. The Burgers vector plays an important role in determining the direction of dislocation line.

What is a Burger vector and how does it relate with dislocation?

The Burgers vector associated with a dislocation is a measure of the lattice distortion caused by the presence of the line defect. The diagram shows the convention for measuring the Burgers vector.

What does the Burger vector indicate?

The Burgers vector, named after Dutch physicist Jan Burgers, is a vector, often denoted b, that represents the magnitude and direction of the lattice distortion of dislocation in a crystal lattice.

What is a Burgers vector of a dislocation and what is its form in an FCC crystal?

A Burgers circuit is any atom-to-atom path taken in a crystal containing dislocations which forms a closed loop. The difference between the two enclosures above is the Burgers vector (clockwise circuit). The Burgers vector of an edge dislocation is normal to the line of the dislocation.