Synergistic effects of rhenium alloying and ion channeling on helium irradiation blistering in tungsten: an <i>in situ</i> helium ion microscopy study

Abstract The effects of helium (He) irradiation on tungsten (W) surfaces have been of intense interest for plasma-facing materials research in nuclear fusion. This study explores the synergistic effects of rhenium (Re) alloying and ion channeling on irradiation blistering in W under 30 keV He ion exposure. Using in situ helium ion microscopy, coupled with electron backscatter diffraction and cross-sectional transmission electron microscopy, we have examined the morphological evolution of both channeling and non-channeling grains in pure W and W–25Re (atomic %). The findings show that crystallographic orientation primarily dictates the pathways of He implantation and accumulation, while Re alloying alters the material’s mechanical properties and He–vacancy interactions. Channeling grains in pure W demonstrate larger surface blisters and deeper subsurface bubbles and cracks. By comparison, while the addition of Re tends to reduce the He implantation range, it simultaneously promotes blistering deformation through enhanced plasticity. Consequently, the synergistic effects of ion channeling and Re alloying leads to the formation of the largest blisters in the channeling grains of W–25Re, offering new insights into the performance of W-based materials in fusion environments.