Microcracks

A Microcrack occurs where internal broken bonds create new surfaces.

They are about 10 µm in size and there is a tendancy to form on the surface of a solid rather than in the bulk.

They also form at grain boundaries and other regions of disorder. The region across which the bonds are broken is known as the separation plane.

Microcracks are formed when there is abrasion (or impacts) with dust particles.They are important in determining how, and where, a solid may fracture. When a crystal has more than one type of atom, there will be Chemical as well as Physical disorder in the grain-boundaries.

Volume Defects:

Volume defects are Voids, i.e. the absence of a number of atoms to form internal surfaces in the crystal. They have similar properties to microcracks because of the broken bonds at the surface.

Amorphous materials and Polymers:

Since they are not just distortions from a perfect crystal structure, Microcracks and Voids can exist in both Crystalline and Amorphous solids.

Polymers can have partly crystalline regions so may also have all of these kinds of defects.