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

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