A numerical model based on the simulation of temperature and stress field is established to describe a diffusion process on High Current Pulsed Electron Beams (HCPEB) treatment. The calculation method and results are shown in this paper. The model and the method can also be used to solve other diffusion processes under thermal impactions. It is shown that concentration flow still plays a major role in the diffusion process; diffusion decreases after several times of pulses; diffusion effects are relatively significant if impurities lie on the surface. This is the theoretical basis of the duplex treatment of surface alloying by HCPEB. Comparing with some experimental results and related calculations

we can find that the diffusion activation energy will significantly decrease during HCPEB treatment due to a high concentration of vacancies induced by bombardment; the convective mixing process will play a major role in diffusion treatment if the surface is in melt.