A molecular dynamics simulation study of temperature and depth effect on helium bubble releasing from Ti surface

Using molecular dynamics simulation, the effect of environment temperature and depth of helium bubble on its volume, pressure and releasing process in metal Ti is researched. First, through studying the statuses of helium bubble at different depths at 300 K, the regularity of helium bubble shape, volume and pressure is acquired. The results show that with depth augmenting, the pressure increases gradually, while the volume decreases, but these two parameters keep around some level when depth is greater than 2.6 nm. Then, the evolution of model system with helium bubble at various temperatures is simulated. On the whole, the critical releasing temperature increases with depth. Finally, the mechanism of helium bubble releasing from Ti surface is explained. It is found that the bubble would tear the Ti film above it when its pressure is greater than the tensile strength of metal film, and then helium atoms will release from the metal.