Microscopic Aspects of Cleavage Fracture

When a polycrystalline sample is deformed, the deformed grains are constrained by the surrounding grains

• This is necessary to maintain continuity of the material

If the grains are not constrained and allowed to deform as single crystals, gaps form and grains overlap

• This occurs due to the fact that the slip planes in each of the grains is oriented differently form one another and react differently to the applied strain