A<unk>  refers to a rapid cooling. In polymer chemistry and materials science,<unk> ing is used to prevent low-temperature processes such as phase transformations from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and kinetically accessible. For instance, it can reduce crystallinity and thereby increase toughness of both alloys and plastics (produced through polymerization).
In metallurgy, it is most commonly used to harden steel by introducing martensite, in which case the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable.  In steel alloyed with metals such as nickel and manganese, the eutectoid temperature becomes much lower, but the kinetic barriers to phase transformation remain the same. This allows<unk> ing to start at a lower temperature, making the process much easier. High speed steel also has added tungsten, which serves to raise kinetic barriers and give the illusion that the material has been cooled more rapidly than it really has. Even cooling such alloys slowly in air has most of the desired effects of<unk> ing.
Extremely rapid cooling can prevent the formation of all crystal structure, resulting in amorphous metal or "metallic glass".
When an electrical current is flowing through a cryogenic superconductor, a slight temperature rise can cause a loss of superconductivity, which leads to resistive heating and a sudden temperature rise.  This phenomenon is also called<unk> ing"
Quench
Rales
Heave
Torque
Cramp
Idose
Itch
Alder