Soldering terminology

Heat released when a substance at a constant temperature passes from liquid into solid phase. Conversely, a substance takes up heat when it passes from solid state into liquid state without changing its temperature. The latter amount of heat is known as heat of fusion and is equal in magnitude with the heat of crystallization. Temperature values can be derived from the change in the heat of crystallization in the cooling curves where phase transitions take place and phase diagrams can be created based on these results.