ABSTRACTThe technique of picosecond electron diffraction is used to time resolve the
laser-induced melting of thin aluminum films. It is observed that under
rapid heating conditions, the long range order of the lattice subsists for
lattice temperatures well above the equilibrium point, indicative of
superheating. This superheating can be verified by directly measuring the
lattice temperature. The collapse time of the long range order is measured
and found to vary from 20 ps to several nanoseconds according to the degree
of superheating. Two interpretations of the delayed melting are offered,
based on the conventional nucleation and point defect theories. While the
nucleation theory provides an initial nucleus size and concentration for
melting to occur, the point defect theory offers a possible explanation for
how the nuclei are originally formed.
Cumulative fatigue damage in thin aluminum films evaluated non-destructively with lasers via zero-group-velocity Lamb modes
