Abstract
For fast heating, solid-liquid phase transition is generally assumed to be an isochoric process related to the ion temperature. However, the experimental studies of fast melting process do not completely agree with the theory. We discuss the validity of the isochoric assumption for fast heating by considering the fast melting of aluminum and gold thin films. The results show that solid-liquid phase transition can occur due to the foil expansion in a picosecond time scale, without significant ion heating, for deposited energies of the order of the melting enthalpy. The estimated melting time for gold thin film irradiated by a short laser pulse is in agreement with experimental measurements.