金属钨中氦行为的分子动力学模拟

采用分子动力学方法模拟了氦在金属钨中的扩散聚集行为. 首先,建立了氦与钨原子间相互作用势,短程部分采用ZBL势形式,长程部分采用从头算法数据,实现了两者之间的平滑连接. 通过计算氦在钨中不同间隙位的形成能发现,单个氦原子更易存在于金属钨中的四面体间隙位,这与最新的研究成果是一致的. 在400-1200 K的温度范围内,考察了氦原子在金属钨中的扩散行为,获得了扩散迁移能,其值介于实验值和从头算法结果之间. 最后,研究了氦的聚集行为,从能量的角度考察了氦团簇形成初期的生长机理. 研究发现,在氦团簇形成初期,氦团簇对氦的结合能随着氦团簇的生长有逐渐增大的趋势,说明氦团簇吸收氦的能力逐渐增强. 关键词： 氦扩散 氦团簇 辐照损伤 分子动力学模拟

Molecular dynamics simulation of helium behavior in tungsten matrix

The helium behavior in tungsten matrix is investigated by means of molecular dynamics. Firstly, the He-W potential is created by combining the ZBL potential with the data from an ab intio method. The formation energy calculations predict that the most stable configuration for helium in interstitial position is the tetrahedral site, which is in good agreement with recent research results. The helium diffusion is simulated in great detail in a temperature range from 400 K to 1200 K, and the migration energy is obtained to be between the experimental data and the ab intio calculation result. Finally, the mechanism of helium accumulation in its initial stage is investigated from the viewpoint of energy. It is found that as the helium cluster grows, the binding energy of each additional helium atom to the cluster tends to increase, which is conducible to the further growth of the helium cluster.