Effects of He irradiation on the microstructure and mechanical performance of Li2TiO3

In solid fusion blankets, energetic helium ions produced by the breeding reaction bombard Li2TiO3 and influence its microstructure and mechanical performance. Here, evaluations of the microstructure and mechanical performance are performed for Li2TiO3 irradiated with 2 MeV helium ions. The Raman spectra demonstrate irradiation-induced structural disorders, which are corroborated by transmission electron microscopy micrographs and selected area electron dispersion patterns. Nanoindentation investigations indicate that the hardness is influenced by irradiation damage. At low doses (about 0.018 dpa), the decrease in hardness is caused by dislocation motion and a decrease of the bond density per unit volume. At high doses (about 0.86 dpa), the defect clusters formed impede the mobility of dislocations, which is the main reason for the increase in hardness. Based on hardness theories and Raman spectra, the decrease in bond length is considered to be another reason for the increase in hardness.