  Control of the crystallization process at the microscopic level makes it
possible to generate the nanocrystalline samples with the desired structural
and morphological properties, that is of great importance for modern industry.
In the present work, we study the influence of supercooling on the structure
and morphology of the crystalline nuclei arising and growing within a liquid
metallic film. The cluster analysis allows us to compute the diffraction
patterns and to evaluate the morphological characteristics (the linear sizes of
the homogeneous part and the thickness of the surface layer) of the crystalline
nuclei emergent in the system at different levels of supercooling. We find that
the liquid metallic film at the temperatures corresponded to low supercooling
levels crystallizes into a monocrystal, whereas a polycrystalline structure
forms at deep supercooling levels. We find that the temperature dependence of
critical size of the crystalline nuclei contains two distinguishable regimes
with the crossover temperature $T/T_{g}\approx1.15$ ($T_{g}$ is the glass
transition temperature), which appears due to the specific geometry of the
system.
