Evolution of defects in titanium grade 2 under Ti2+ ion irradiation.

The complexity and diversity of microstructure involved in titanium alloys make it rather difficult to quantitatively describe defect evolution due to irradiation. This paper focuses on defect evolutions of commercially pure titanium grade 2 under Ti2+ ion irradiation considering the effect of dose (0.6 and 3 dpa), temperature (300°C and 430°C) and flux (15:1 ratio). An irradiation damage profile was predicted using SRIM software to obtain a homogeneous damage on at least 500 nm depth for TEM observations and simulated using JANNUS-Saclay facility. The details regarding the quantification methodologies of the defects from dark field images are provided, as are the origins of the associated uncertainties. In addition to a tangled dislocation network, presence of the -type and -component loops is observed. The latter was scarcely reported in the literature in the case of titanium alloys. At low temperature, the size distribution of the -type dislocation loops remained similar regardless of the dose and flux whereas these parameters have highly influence at 430°C. A widening of the size distribution and an increase of the threshold incubation dose (TID) was noted with the temperature. In the case of the -component loops, it was shown that the nucleation occurred in spite of the 0.6 dpa low dose.