Behavior of tritium in aluminum-lithium alloys

The behavior of radiation induced gas bubbles in Al-Li alloys was observed by means of ³H autoradiography. The autoradiographs were compared with photomicrographs of the corresponding areas. Autoradiography proved to reveal the gas bubbles in the alloys more distinctly than photomicrography. It was found that the bubbles first appeared at the grain boundaries and subgrain boundaries, and there also appeared depleted zones along the grain boundaries. This was followed by crystallographic alignment of the bubbles when heated to higher temperatures. In the case of large gas concentrations, bubbles as large as 5 μ in diameter were observed in specimens heated for 1 hr at 500℃. Bubbles precipitated along the boundaries of recrystallized grains in a specimen of irradiated Al-2.7 w/0 Li when it was tension stretched and then heated for 1 hr at 300℃. (author)