Latent Heat of Fusion
The amount of thermal energy required to change a unit mass of a substance from solid to liquid at constant melting temperature.
Governing formula
Q = m L_f
SI unit
J/kg
In depth
Energy absorbed during melting goes into breaking crystal lattice bonds rather than raising system temperature.
Examples in the real world
Water's latent heat of fusion ($334,000 J/kg$) making ice cubes highly effective at cooling drinks without immediate temperature jumps.