Differential effects of heavy ion irradiation on the tungsten matrix and fiber components in composite materials

In the extreme operating environment of nuclear fusion reactors, direct irradiation by 14 MeV high-energy neutrons significantly degrades the service performance of plasma-facing materials. As an innovative plasma-facing material, tungsten fiber reinforced tungsten composites have rarely been systematically studied for their irradiation resistance. In this work, 7.5 MeV high-energy Au 2+ ions were used to irradiate the tungsten matrix and tungsten fibers in the tungsten fiber-reinforced tungsten matrix composites (Wf/Wm) prepared previously by our research group, respectively. Using characterization methods such as spherical aberration-corrected transmission electron microscopy (AC-TEM), in-situ mechanical experiments, and nanoindentation, we focused on investigating the effects of irradiation on the microstructure and mechanical properties of the material, and compared the differences in irradiation resistance between tungsten fibers and the tungsten matrix. The main conclusions are as follows: (1) Under room-temperature irradiation, the dominant defect type in both the tungsten matrix and tungsten fibers is the 1/2 < 111 > dislocation loop; (2) When the irradiation dose ranges from 22.5 to 45 dpa, the defects in the tungsten matrix tend to saturate, with an ultimate compressive strength of approximately 2500 MPa; (3) At an irradiation dose of 45 dpa, the defects in tungsten fibers remain unsaturated, and the irradiation-induced hardness increment is only 0.32 GPa (much lower than the ∼ 1 GPa of the tungsten matrix), demonstrating the superior irradiation resistance of tungsten fibers.