smeltevarmen

Smeltevarmen, in materials science, refers to the latent heat of fusion—the amount of energy required to change a substance from solid to liquid at its melting point without a change in temperature. This energy is stored in the material’s bonds and lattice as it transitions to the liquid phase. The symbol Lf is commonly used, and the total heat required to melt a mass m is Q = m × Lf. Specific latent heat is given per unit mass (J/kg) and molar latent heat per mole (J/mol).

Latent heat of fusion varies widely among materials. For water, Lf is about 333.6 kJ/kg at 0 °C. In metals, values are typically higher, and the range can be broad depending on the material and its crystal structure. As a rough guide, metals often have latent heats from roughly 0.3 to 15 MJ/kg. For example, aluminum is relatively high, while iron lies in the lower end of the metal range. Impurities, alloying elements, and the presence of phase mixtures can broaden or shift the melting region.

Measurement and applications. Smeltevarmen is crucial for energy budgeting in smelting, casting, welding, and alloy processing. During heating, sensible heat raises the temperature of a solid to its melting point; once melting begins, added heat goes into changing the phase at a constant temperature. This affects furnace design, heating schedules, and energy efficiency. In laboratory settings, differential scanning calorimetry (DSC) and related methods are used to determine Lf by measuring heat flow during controlled heating and cooling.

See also: phase transitions, latent heat, phase diagrams, calorimetry.