金属钨中氦团簇扩散与形核特性的分子动力学研究

The diffusion and nucleation characteristics of helium clusters in tungsten by molecular dynamics simulation

本文应用分子动力学方法模拟研究了氦团簇在金属钨中的扩散特性,得到了不同大小团簇的扩散系数,结果表明氦团簇越大,扩散越慢.氦团簇越大越容易激发出自间隙钨原子,且大的氦团簇只需要很低的钨基体温度即可激发.在金属钨中加入125个氦原子(氦浓度低于0.1%),研究了氦团簇的形核特性.通过比较氦团簇、自间隙团簇和空位团簇3种缺陷的尺寸分布发现,氦团簇的尺寸在800 K达到最大值,其它两种缺陷尺寸随温度的增加而逐渐增大.

The diffusion and nucleation characteristics of helium clusters in tungsten were studied by molecular dynamics simulation.The diffusion coefficients of different sizes of helium clusters were obtained.The results showed that the bigger helium cluster is,the slower it migrates and the easier for it to kick out a self-interstitial tungsten atom.When the helium cluster is large enough,it can push a tungsten atom away from its lattice,even at a very low temperature.125 helium atoms were planted into the tungsten host and then the nucleation mechanisms of helium clusters were studied with molecular dynamics simulation.It can be concluded that the size of helium clusters achieved its peak value at 800 K; however,the other two defect clusters（self-interstitial atoms and vacancy clusters） increase with the increase of temperature.