Using molecular dynamics simulation, we investigate the dynamic evolution characteristics of He bubble and its effects on void nucleation-growth and thermomechanical properties in single crystal Al during spallation. The evolution process of bubble includes four stages: slow and independent expansion, rapid and independent expansion, deceleration expansion due to inter-bubble interaction and merging, and fast expansion after merging. The bubble radius-time relation is approximately linear both before and after merging and the corresponding expansion rates are obtained. The mechanism of bubble expansion (growth) in solid metal under dynamic tension involves plastic deformation via dislocation nucleation and movement and temperature rising around the bubble. The growth toward neighboring bubble leads to the overlap of plastic deformation regions that promotes local melting. The flows of melted atoms along both normal and tangential directions of the two bubbles result in the thinning and breaking of the inter-bubble ligament, and thus bubble merging occurs. In melted metal, the tension deformation under velocity gradient leads to bubble growth and coalescence. He bubble impedes the nucleation and growth of nearby voids and the expanded bubble absorbs grown voids when they contact. Such suppression enhances with the increase of bubble size or density while attenuates with the increase of shock strength. The number of nucleated voids is much lower and the average radius of voids is smaller for the sample with He bubbles in solid state. After melting, the reduction in quantity gets smaller and the radius becomes a little higher due to the suppression on continuing nucleation of voids. The bubble behavior and its influence on void evolution result in the variation of spall mechanism: the expansion and merging of He bubble play the leading role, independent on shock strength, bubble density, or bubble size. The effects of He bubble on temperature and stress are also addressed.

使用分子动力学模拟，我们研究了He气泡的动态演化特征及其对散裂过程中单晶Al中空核形生长和热机械性能的影响。气泡的演化过程包括四个阶段：缓慢独立膨胀，快速独立膨胀，气泡间相互作用和汇合引起的减速膨胀，汇合后快速膨胀。在合并之前和之后，气泡半径-时间关系近似为线性，并且获得了相应的膨胀率。固体金属在动态张力下的气泡膨胀（增长）机制涉及位错成核，运动和气泡周围温度升高引起的塑性变形。向邻近气泡的增长导致塑性变形区域重叠，从而促进局部熔化。沿着两个气泡的法线方向和切线方向的熔化的原子流导致气泡间韧带变薄和破裂，从而发生气泡合并。在熔融金属中，速度梯度下的张力变形会导致气泡生长和聚结。他的气泡阻碍了附近空隙的形核和生长，并且膨胀的气泡在接触时吸收了成长的空隙。这种抑制随着气泡尺寸或密度的增加而增强，而随着冲击强度的增加而减弱。对于固态He气泡的样品，有核空隙的数量要少得多，并且平均空隙半径要小。融化后 由于抑制了空洞的持续成核，数量的减少变小并且半径变大。气泡行为及其对空洞演变的影响导致剥落机制的变化：He气泡的膨胀和合并起着主导作用，而与冲击强度，气泡密度或气泡大小无关。还讨论了氦泡对温度和应力的影响。