Melting (also known as
fusion) is a physical process that results in the
phase transition of a
substance from a
solid to a
liquid. This occurs when the
internal energy of the solid increases, typically by the application of
heat or
pressure, which increases the substance's
temperature to the
melting point. At the melting point, the ordering of
ions or
molecules in the solid breaks down to a less ordered state, and the solid
melts to become a liquid. An object that has melted completely is
molten (although this word is typically used for substances that melt only at a high temperature, such as molten
iron or molten
lava).
