The crystallization of vacuum-deposited amorphous Dy-35at.%Cu thin films was studied by transmission electron microscopy and electron diffraction. The transmission electron micrographs allowed us to follow the nucleation and subsequent growth of DyCu crystals within the amorphous matrix. The crystallization process is characterized by its sharp onset at 150 °C. The temperature dependence of the nucleation rate agrees with simple models. The growth rate increases linearly with temperature. The characteristic exponent n in Avrami's equation corresponds to a two-dimensional interface-controlled growth. The results allowed us to determine the free energy of critical nucleas formation (0.18 eV) and also the free energy associated with atomic migration (1 eV).