Irradiation-induced precipitation in V-4Cr-4Ti alloys studied using three-dimensional atom probe

To investigate neutron irradiation effects on the precipitation behavior of Ti(O,N,C) in V-4Cr-4Ti alloy, chemical and structural analyses were conducted using a laser-assisted local electrode three-dimensional atom probe. Ti(O,N,C) precipitates were observed after irradiation at 333 and 673 K. These NaCl-type precipitates mostly consisted of V, Ti, Cr, O, and C. The chemical composition of the precipitate was estimated as about V39Cr2Ti5CO3 at both irradiation temperatures. This result suggests that most of the Ti sublattice presumed to be replaced by V and O, N, and C sublattice are instead occupied by vacancies. Therefore, compositionally modified V39Cr2Ti5CO3 precipitates might form with larger volume fractions than TiO precipitates.