Explanation: Frank-Read source is a mechanism which explains dislocation multiplication. It explains dislocation multiplication in well spaced slip planes on deformation.

Explanation: σc ≈ 2T/lb, here l is free length, T is tension and b is Burgers vector. The stress required to activate the largest Frank-Read sources would be small. It varies from crystal to crystal.

Explanation: Density of dislocations increases during plastic deformation. It is due to the Frank-Read source. It increases by an order of 2 to 4 in magnitude depending on the degree of deformation.

Explanation: Annealing heat treatment reduces dislocation density in crystal. It is due to annihilation of dislocations on high temperature. Dislocation density ranges from 1010-1012 m-2.

Explanation: Heavy plastic deformation causes rapid increase in dislocation density in crystal. It is in range 1014-1016 m-2 . It causes strain hardening effect in crystal.

Explanation: BCC metals show some covalent characteristic due to ‘d’-orbital bonding. Therefore, these metals show less ductility. FCC metals show high ductility and wide dislocations so these can be cold worked to the largest extent.

Explanation: Cold working of materials causes an increase in dislocation density. It is due to the formation of Frank-Read source. Higher dislocation density enhances yield strength due to work hardening.

Explanation: Dislocation generation takes place on planes with Frank-Read source. These sources produce dislocation loops on application of stress. It can be understood by Frank-Read source mechanism.

Explanation: The stress required is given by τ = 2Gb/x. Here G is shear modulus, b is Burgers vector and x is a distance between pinning sites. Hence it is inversely proportional to x.

Explanation: Frank read source forms by immobile pinning sites. These sites may form by other solute atoms, second phase particles or intersection with other dislocations. These generate dislocation loops on applying stress.

Explanation: The points say X and Y, remain immobile in applying stress. These are generally pinned by second phase particles. Hence, they are known as nodal points.

Explanation: Bowing (R) is given by R ∝ Gb/τ. Here G is shear modulus, b is Burgers vector and τ is applied stress. Hence bowing increases with increase in applied stress.