We are studying defects, sub-nanoscale precipitates and interface segregations of impurity/solute atoms in materials. Our target extends from nuclear materials such as reactor pressure vessel steels and shroud stainless steels to semiconductors such as silicon and germanium. We employ positron annihilation, atom probe tomography, electron microscope, etc. By combining various theoretical calculations with the above experiments, we are clarifying the formation and microscopic structures of these defects, precipitates and interface segregations.
Materials Design Division
Irradiation Effects in Nuclear and Their Related Materials Research Laboratory
Prof.Yasuyoshi NAGAI
- Assoc. Prof. Koji INOUE
- Assist. Prof. Peng SONG
Towards Revealing Irradiation-Induced Defects and Controlling Their Function
nuclear materials, semiconductors, positron, atom probe tomography, electron microscopy
3D structural – chemical analyses by combining electron tomography by STEM with atom probe tomography and positron annihilation spectroscopy enable to directly reveal relationship between formation of irradiation induced fine defects and impurity segregation/clustering.
TEM image for voids and APT map for rhenium (Re) obtained from the same area of the needle specimen in tungsten irradiated in the fast neutron experimental reactor. By comparing the TEM image and the APT map, a one-to-one correspondence is clearly obtained between the voids in the TEM image and the Re-enriched clusters in the APT map. The voids decorated with transmuted rhenium atoms are directly observed.