金属钛中氦团簇生长行为的分子动力学研究

Molecular dynamics simulation of helium cluster growth in titanium

运用分子动力学方法模拟了常温下金属钛中氦团簇的生长过程.从能量的角度考察了氦团簇的生长机理.研究发现,随着氦团簇的生长,在氦团簇周围逐渐形成位错环缺陷,氦团簇与氦原子的结合能有逐渐下降的趋势,当氦团簇生长到一定尺寸时会通过发射周围缺陷以使得结合能上升,从而增强了进一步吸收氦原子的能力.模拟还发现,随着氦团簇的继续生长,氦团簇的形状由原来的不规则结构逐渐变成了较为规则的棱柱形结构,在随后的生长过程中其生长仅在(001)平面进行,沿[001]轴的厚度几乎不变.

The growth of helium cluster in titanium crystals at room temperature has been simulated detailedly by means of molecular dynamics. The mechanism of helium cluster growth in metal materials has been investigated from the viewpoint of energy. It is found that, as the helium cluster grows, dislocation loops are formed around the cluster and the binding energy of each additional helium atom to these clusters tends to decrease. However, at certain point in the growth process, the defects escape rapidly and the binding energy increases, helping the further growth of the helium cluster. As more helium atoms are introduced, the shape of the helium cluster is transformed gradually to a prismatic morphology from the irregular morphology and its thickness is always observed to be about 1.2 nm, without any obvious variation with degree of helium filling.