Background: Understanding of helium state is important for the materials used in radiation surroundings. Most mechanical damage starts with a change in the microstructure of the material. Purpose: To study the behavior of helium in the material

a helium contained Al-B alloy Al0.4wt%B was prepared using 10B (n

α) nuclear reaction by reactor thermal neutron irradiation. The helium atoms density reached to 6.2×1025 m?3. Methods: The synchrotron small angle X-ray scattering (SAXS) was employed to study the helium state at different temperatures. The X-ray and neutron diffraction were used to inspect the lattice change. The tempered samples were observed with transmission electron microscope (TEM) to confirm the helium bubbles. Results: SAXS analysis shows the volume fraction of helium bubbles significantly increased with temperature. The radius of helium bubbles increased to about 10 nm at 700 oC

which is the similar size of scatters at room temperature. TEM results show some obvious pores and particles existed in the sample at room temperature and disappeared after 500 oC

and helium bubbles appeared increasingly with temperature. The results of SAXS and TEM are consistent. X-ray and neutron diffraction analysis show there is no visible second phase

the doped B increased and the produced Li and He further increased the lattice constant. The heat treating makes He atom escape from the lattice to form He bubble at grain boundaries and results in a drop of lattice. The first-principles calculation gave the volume changes because of introducing B

Li and He and explained this lattice decline. Conclusion: A helium contained Al-B sample was successfully prepared and there is no observable helium bubble in the irradiated sample. Heat treating promoted the helium atom aggregation and helium bubble formation

and removed defects and damages. The SAXS information for helium bubble is observed only in tempered sample. Abstract