» "Molten" redirects here For the Japanese company, see Molten Corporation; or see Molton or Moulton. Melting (sometimes called fusion) is a physical 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 or pressure, resulting in a rise of its temperature to the melting point, at which the rigid ordering of molecular entities in the solid breaks down to a less-ordered state an… (More on Melting)