强流脉冲电子束轰击作用下的扩散模型及其数值计算

在温度场和应力场计算的基础上建立了强流脉冲电子束轰击作用下的扩散模型，并给出了数值方法及其数值解。该模型与方法同样适用于其它高能束流作用下的扩散过程。计算表明，浓度扩散流仍然是影响扩散的主要因素；而轰击超过一定次数后，扩散的作用将减弱；当边界条件为表面扩散时，扩散进行较快，这是表面涂覆加脉冲电子束后处理快速表面合金化工艺的理论基础。对实验结果和理论结果的对比分析表明，在脉冲轰击下，扩散激活能随空位浓度的增加而下降，从而加速扩散过程；在表面有熔化的情况下，则液态时的对流混合作用是主导因素。

Numerical model and simulation of diffusion process under High Current Pulsed Electron Beam (HCPEB) treatment

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.