Study on distribution characteristics of helium bubble in aluminum

The industrial pure aluminum was implanted by He ion with the dose of 3 × 10²⁰ m^-2 in the injection energy of 500 keV. The SRIM software was carried to simulate and predict the highest He atom concentration located at the position, and the position is 1.8 μm away from the surface. The sample with He ion implantation was aged for 192 h at 190℃ to promote the nucleation and growth of helium bubbles. Distribution of helium bubbles in the depth was observed by transmission electron microscope (TEM). The TEM results show that the highest helium atom concentration is at the position of 1.8 μm away from the surface, which is accord with the results by SRIM software. It is found that the size of helium bubbles formed on the grain boundary is larger than that formed in grain, which indicates that the grain boundary is beneficial to the formation and growth of helium bubbles. At the same time, there exist large differences about the size of helium bubbles in different grains beside the same grain boundary, which shows that grain orientation may have a significant influence on coalescence and growth process of helium bubbles. (authors)