Pores and cracks are not localized to a particular point or edge, but have sizes much larger than atomic dimensions.

Dislocation involves sliding of crystal blocks over one anor along definite crystallographic plane which results in a slip.

The American Society for Testing and Materials (ASTM) has prepared several standard comparison charts, all having different average grain sizes.

Substitution as name suggests it deal with substituting an atom or element in empty gaps present in crystalline solid which are commonly called as a vacancy.

For edge dislocation nature of dislocation line is perpendicular.

When no foreign atom is present in crystal lattice and same kind of atoms are forming defect n it is called as an intrinsic atom. When re is a presence of an additional atom in crystal lattice, it is called extrinsic defect and hence y are classified according to source of atom.

Positron annihilation technique is used to measure resistivity after quenching, Thermal imaging this technique is used to measure concentration of vacancy to determine activation energy for its formation and Photo micrographic technique is used to determine grain size of polycrystalline materials.

Ramp that is traced around dislocation line is spiral or helical that?s reason it is called screw dislocation.

In substitution defect, particles of or species having similar sizes replace host particles in a lattice whereas interstitial defect occurs when particles of same species are present at interstitial voids.

Line defects are mainly dislocations which can be broadly classified into two distinct defects. These two dislocations are called edge dislocation and screw dislocation.