melted

Melted, in common usage, describes a substance that has changed from a solid to a liquid due to the application of heat. The temperature at which this occurs is the melting point, a characteristic property of materials. Below the melting point, a material exists as a solid with a definite structure; at and above, it becomes a liquid with fluid behavior. Some materials may decompose before they melt.

The melting process is an endothermic phase transition that requires latent heat of fusion. For pure crystalline substances, the melting point is precise; for impure or mixed substances, it occurs over a range of temperatures. Impurities typically depress and broaden the melting range. At small scales, nanoparticles have lower melting points due to surface energy effects. Eutectic mixtures can melt at lower temperatures than their constituents.

Common examples include ice, which melts at 0°C under standard pressure; metals such as iron and copper melt at much higher temperatures; waxes and polymers melt at varied temperatures depending on composition. Some materials do not melt under practical conditions and instead decompose or sublimate. In geology and material science, melting plays a key role in processes such as magma formation, alloy production, and glass formation (which forms by rapid cooling of melted silica).

In industrial settings, controlled melting is essential for casting, forging, soldering, and welding. The term melted can also describe foods (for example, melted cheese) or plastics and chocolate that have softened into liquids. The state is typically reversed by cooling, which releases latent heat as the liquid solidifies into a solid.