Surface damage evolution during helium plasma irradiation of W-Y2O3 composite materials in different grain orientations

Tungsten (W) is the preferred material for first walls. In this study, a linear plasma device was employed to irradiate two surfaces of a W-Y₂O₃ (WYO) composite rod with low-energy helium plasma, with one surface perpendicular and the other parallel to the rod’s axial direction. The evolution of surface damage on WYO due to plasma irradiation was characterized by scanning electron microscopy, while the effect of grain orientation on irradiation damage resistance was analyzed through electron backscatter diffraction and white light interferometry. Results reveal that under varying irradiation doses, the surface of polycrystalline W exhibits three distinct morphologies: wavy, pyramidal, and step-like structures. A comparison of the two surfaces shows that the extent of irradiation damage is highly dependent on grain orientation. Specifically, grains oriented along the [101] direction demonstrate the strongest resistance to irradiation damage, whereas those with a [111] orientation exhibit the weakest resistance. Further analysis suggests that differences in atomic binding energies on various crystal planes, along with the channeling effect of adjacent planes, may significantly influence the observed surface morphologies.