Effect of high energy helium ion irradiation on microstructure and mechanical response of CLAM steel

The blanket structural material of fusion reactor will induce radiation damage during the period of service. As the preferred structural material of thermonuclear fusion reactor, it is necessary to study its radiation behaviour. High energy helium ions were used to conduct irradiation experiments on CLAM steel, and the microstructure evolution and mechanical properties of CLAM steel during irradiation were studied using nanoindentation experiments combined with atomic force microscopy (AFM). The results show that dislocation loops and He bubbles are induced in irradiated CLAM steel, and the density and size of dislocation loops and He bubbles increases with the increase of irradiation dose. The results of the indentation experiment indicate that CLAM steel has a significant irradiation hardening effect after irradiation. The degree of irradiation hardening increases with the increase of irradiation dose, but when the irradiation dose increases to some extent, the irradiation hardening effect weakens. The effect of microstructure evolution on irradiation hardening effect is also discussed by DBH model and FKH model. The results of indentation morphology analysis show that the range of material protrusions around the indentation decreases with the increase of irradiation dose, the stacking height increases, and shear bands appear in the stacking around the indentation after high dose irradiation, indicating a significant increase in brittleness of CLAM steel after irradiation.