  The isothermal nucleation kinetics in Al-Sm metallic glasses with low Sm
concentrations (xSm) was studied using molecular dynamics simulations in order
to calculate time-temperature-transformation curves. The average delay time of
Al nanocrystal nucleation was found to increase exponentially with xSm, whereas
the estimated critical cooling rate necessary to avoid crystallization
decreases exponentially with xSm. Sm solutes were found to suppress Al
nucleation by increasing the attachment barrier and therefore by reducing the
attachment frequency. The analysis shows that the attachment of Al to the
evolving nucleus has the same characteristics as Al diffusion within the
amorphous matrix and they both take place heterogeneously via collective
movement of a group of Al atoms.
