Helide Formers Mitigating Helium Embrittlement of Polycrystalline Materials

Fusion power holds great promise as the ultimate energy source. However, achieving true sustainability in civilian fusion requires addressing the embrittlement of polycrystalline materials used in fusion reactors, which is caused by transmutation helium and leads to premature materials failure often within a year. Here it is experimentally demonstrated that nanodispersions with constitutional vacancy-like atomic-scale free volume can divert and securely store helium within their “bulk lattices,” significantly delaying critical helium damage in polycrystalline matrices. The selected nano-phase possesses a moderately large atomic-scale free volume to store helium while undergoing lattice distortions upon helium absorption. These distortions cause observable changes in X-ray diffraction (XRD) patterns, distinct from changes resulting from other factors like radiation damage. By comparing grazing incidence XRD patterns with <i>ab initio</i> computed patterns, it is shown that the added nano-phase can store helium up to ~10 at% within its bulk lattice, forming a “helide compound.” Incorporating just 1 vol% of the nano-phase reduced helium bubble size and number density by &gt;20% and &gt;50% respectively. These findings suggest that 1–2 vol% of similar nano-phases can effectively accommodate a few thousand appm of bulk helium, expected to be generated over a 10-year operational period.