Sub-micron fracture
A sub-micron fracture was a minuscule fracture that could be caused by neutron fatigue.

A sub-micron fracture in the metal casing of a dilithium chamber hatch replaced at Earth Station McKinley in 2367 was the cause for an explosion in the 's dilithium chamber, and not sabotage by the Klingon spy J'Dan, as was originally suspected. The fractures were detected by means of microtomographic analysis. ()

See also 
 Microfracture
Physics