State Key Laboratory for Environment-Friendly Energy Materials;
Southwest University of Science and Technology;
Mianyang 621010;
China;
Sino-French Institute of Nuclear Engineering and Technology;
Sun Yat-sen University;
Zhuhai 519082;
China;
Institute of Modern Physics;
Chinese Academy of Sciences;
Lanzhou 730000;
China;
martensitic steels; Fe and He co-irradiation; He bubbles; transmission electron microscopy;