Briefly describe a twin and a twin boundary Cite the differe

Briefly describe a twin and a twin boundary. Cite the difference between mechanical and annealing twins.

Solution

A Twin Boundary is an interface such that the crystals on either side of a plane are mirror images of each other.The boundary between the twinned crystals will be a single plane of atoms.There is no region of disorder and the boundary atoms can be viewed as in relation to the crystal structures of both twins.The region on one side of this boundary is known as twin.
Mechanical twins are produced as a result of mechanical deformation and generally occur in body centered cubic structured and hexagonal close packed structured metals.They are produced due to immediate result of applied stress in the usual manner.
Annealing twins are formed during annealing i.e heat treatments,thermal stress and occurs most oftenly in face centered cubic structured metals.They occur during annealing process after plastic deformation to reduce the internal stress.