Effect of Ta addition on the fuzz formation of additively manufactured W-based materials

As a divertor plasma-facing material, W will experience high-flux plasma irradiation. In particular, severe surface morphology change like fuzz formation can be induced by He plasma irradiation. In this study, fuzz formation on additively manufactured W and W-Ta was investigated. Rolled W, laser-powder-bed-fused (LPBFed) W and W-Ta were exposed to high flux (∼10²³ m^-2 s^-1) He plasma in the linear plasma generator Magnum-PSI with ion energy 12-13 eV at 1273 K. The mean thickness of the fuzz at grain interiors of rolled W, LPBFed W and W-Ta was measured as 0.37 μm, 0.71 μm and 0.23 μm, respectively. The fuzz suppression in LPBFed W-Ta can be attributed to the synergetic effect of solid-solution, dislocation, and secondary-phase nanoparticles. Abnormally grown fuzz was observed near the pre-existing cracks of LPBFed W, while no such structure was found in LPBFed W-Ta. It is found that dislocations play a crucial role in inhibiting fuzz growth. This is confirmed by the difference in fuzz structure in rolled W and LPBFed W, where rolled W has a much greater dislocation density compared to LPBFed W. This work suggests that the fuzz growth kinetics may be tuned by tailoring the microstructures using the LPBF technique.