The role of hydrogen in the synergistic effect between hydrogen and displacement damage on defect formation in RAFM steel

摘要: The presence of hydrogen will affect the formation of irradiation defects in reactor structural materials, which in turn will influence the degradation of their mechanical properties. A deeper understanding of the mechanisms behind irradiation effects in structural materials in the presence of hydrogen poses an important scientific challenge in the field of fusion and fission energy. Reduced-activation ferritic/martensitic (RAFM) steel, a potential structural material for fusion and fission reactors, was selected as the research material. Using positron annihilation Doppler broadening spectroscopy, it was characterized that a significant amount of hydrogen atoms in the H + irradiated RAFM steel are captured in vacancies, resulting in the formation of relatively stable vacancy-H complexes. Furthermore, the first-principles calculations revealed that this behavior of hydrogen atoms being captured at vacancies inhibits the recombination of vacancies and SIAs generated by cascade collisions, especially when the concentration of hydrogen is high, thereby promoting the formation of irradiation defects.