Quantification of evaporation parameter and determination of evaporation mechanism

Evaporation parameter of solute atoms segregated on surfaces is quantified and its physical meaning is revealed to be an integrated effect of segregation, diffusion, and evaporation. Evaporation activation energy is formulated and its minimum can be used to estimate the binding energy between solute and solvent atoms. Evaporation activation energy of Mg from the surface of Al-0.8 wt%Mg alloy is determined to be very close to the binding energy between Al atom and Mg atom, indicating segregated Mg is adsorbed on the surface. Excellent agreement between theoretical calculations and experimental results provides a quantificational approach to uncover the evaporation mechanism.