Effects of solid transmutation and helium on microstructural evolution in neutron-irradiated vanadium

Pure V and V alloys with B and Cr irradiated in the HFIR to 10 dpa at 400, 500 and 600 °C are examined by TEM. Nine percent of V is transmuted to Cr during irradiation to 10 dpa, and more than 99% of 10B is transmuted to He and Li during the early stage of irradiation. The Cr generation suppresses cavity nucleation near grain boundaries in pure V. However in V–4.9Cr which contains 13at.%Cr after irradiation, cavities concentrate near grain boundaries, and there are few cavities in the matrix. At 400 and 500 °C, the effect of He on the cavity formation is not clearly observed. At 600 °C, B addition enhancese the cavity nucleation in pure V and V–4.9Cr in the matrix. Growth of cavities is also enhanced in pure V which is converted to V–9.4Cr.