Melting
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| Mechanical failure modes | |
|---|---|
| Buckling | |
| Corrosion | |
| Creep | |
| Fatigue | |
| Fracture | |
| Melting | |
| Rupture | |
| Thermal shock | |
| Wear | |
| Yielding | |
Melting is a process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased (typically by the application of heat) to a specific temperature (called the melting point) at which it changes to the liquid phase. An object that has melted completely is molten.
The melting point of a substance is equal to freezing point.
Contents |
[edit] Molecular vibrations
When the internal energy of a gas is increased by the application of an external energy source, the molecular vibrations of the substance increases. As these vibrations increase, the substance becomes more and more ordered.
[edit] Constant temperature
Substances melt at a constant temperature, the melting point. Further increases in temperature (even with continued application of energy) do not occur until the substance is molten.
[edit] The thermodynamics of melting
From a thermodynamics point of view, at the melting point the change in Gibbs free energy (<math>\Delta G</math>) of the Material is zero, because the enthalpy (<math>H</math>) and the entropy (<math>S</math>) of the material are increasing (<math>\Delta H, \Delta S > 0</math>). Melting phenomenon happens when the Gibbs free energy of the liquid becomes lower than the solid for that material. At various pressures this happens at a specific temperature. It can also be shown that:
<math>\Delta S = \frac {\Delta H} {T}</math>
The "<math>T</math>","<math>\Delta S</math>", and "<math>\Delta H</math>" in the above are respectively the temperature at the melting point, change of entropy of melting, and the change of enthalpy of melting.
[edit] Books
- Kleinert, Hagen, Gauge Fields in Condensed Matter, Vol. II, "STRESSES AND DEFECTS; Differential Geometry, Crystal Melting", pp. 743-1456, World Scientific (Singapore, 1989); Paperback ISBN 9971-5-0210-0 (readable online here)
[edit] Other meanings
In genetics, melting DNA means to separate the double-stranded DNA into two single strands by heating or the use of chemicals.
- See also : Polymerase chain reaction
[edit] See also
From To Solid Liquid Gas Plasma Solid Solid-Solid Transformation Melting Sublimation - Liquid Freezing N/A Boiling/Evaporation - Gas Deposition Condensation N/A Ionization Plasma - - Recombination/Deionization N/A
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