[en] This paper reports on the nucleation and transformation kinetics of the amorphous-to-crystal transition in Si films under 1.5 MeV Xe⁺ irradiation investigated by means of in-situ transmission electron microscopy in the temperature range T = 480 - 580 degrees C. After an incubation period during which negligible nucleation occurs, a constant nucleation rate was observed in steady state, suggesting homogeneous nucleation. A significant enhancement in nucleation rate during high energy ion irradiation (6 order of magnitude) was observed as compared with thermal crystallization, with an apparent activation energy of Q_n = 3.9 ± 0.75 eV. Independent analyses of the temperature dependence of the incubation time, the crystal growth rate, and nucleation rate suggest that interface rearrangement kinetics and not the thermodynamic barrier to crystallization are affected by ion irradiation