= Superheating
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Superheating is persistence of a phase above the equilibrium temperature at which a higher-temperature phase becomes favorable. The familiar case is a liquid above its <boiling point> at the imposed pressure, although delayed melting can also be discussed as superheating.
The liquid can remain in a <metastable> state because producing a vapor bubble costs interfacial energy. A sufficiently large bubble overcomes the <nucleation barrier> and grows, converting the liquid and consuming <latent heat>. Smooth clean containers can delay nucleation, while cavities and <boiling chips> provide heterogeneous nucleation sites. The observed temperature of sudden bubble formation therefore need not equal the equilibrium boiling point. The amount of superheating is a kinetic and preparation-dependent observation, rather than a new equilibrium phase boundary.
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