Precipitation in Fe-Cu and Fe-Cu-Mn model alloys under irradiation: Dose rate effects

On the use of charged particles to characterize precipitation in irradiated reactor pressure vessel steels with a wide range of compositions

“…Despite being a powerful characterization tool, APT suffers from a number of potential artifacts such as surface diffusion, trajectory aberrations, multiple hits, pre-emission and variations in the local magnification factor [33,45,[64][65][66]. While these artifacts can be minimized through carefully selected run parameters and advanced reconstruction procedures, they complicate the analysis.…”

“…In turn this results in the erroneous measurements of the precipitate composition and the appearance of physically unrealistic high hit densities of atoms within the precipitate [33,58]. By combining STEM-EDS and multi technique characterization studies (small-neutron scattering, smallangle X-ray scattering, positron annihilation coincidence Doppler broadening, orbital electron momentum spectrum and lifetime measurements and combined electrical resistivity and Seebeck coefficient measurements), it's been clearly shown high concentrations of Fe in the precipitates are an APT artifact [45,64]. Thus the Fe content within the precipitates was excluded from calculations of precipitate size and compositions [33,45,64,66].…”

“…However, there are many differences between NI and CPI as noted in the partial list and dpa rates can strongly affect RED accelerated precipitation [4][5][6]9,25,31,33,37,38,[43][44][45][46].…”

Mn promotes the rate of nucleation and growth of precipitates by increasing Frenkel pairs in Fe–Cu based alloys

“…In reactor pressure vessel (RPV) steels which have a very low Cu content, the Cu precipitates also appear under long-term irradiation, and these Cu precipitates are considered to be the origin of embrittlement of RPV steels which limits the service time of nuclear power plants. [16][17][18][19][20][21][22][23][24][25] Cu precipitate is typical in steels, and therefore investigating the evolution of Cu precipitates is a hot topic.…”

“…For example, the evolution of precipitates in Northwestern University copper alloyed serveries steels (NUCu) has been well characterized, and the mechanical properties, such as hardness were also examined under different treatments. [1][2][3]9 For RPV steels, it is very fortunate that many data on Cu-rich clusters in steels under neutron irradiation have been reported, 16,17,19,21,31 though the data generally are rare for many other materials under neutron irradiation.…”