Soldering terminology

During the cooling of the melt of a eutectic alloy of two metals (A and B), the metal which is present in larger proportion is first to crystallize. The temperature at which the crystal formation occurs in this process is referred to as the liquidus line of A and B. The line obtained when measuring the liquidus temperature of a mixture, i.e. the temperature at which the mixture begins to solidify in function of the composition, is known as the liquidus line or the crystallization curve of the mixture.