Effect of cascade size and damage rate on & alpha;' precipitate stability in Fe-15Cr

Samples of a Fe-15Cr model alloy with an established a' precipitate population were irradiated with 1.25 MeV electrons, 1.5 MeV protons, or 4.4 MeV Fe2+/3+ ions over a range of damage rates to doses of 1 or 10 dpa at 400C to determine the roles of cascade size and damage rate on the stability of a'. Results showed that a' precipitate size and chromium content increased with dpa for electron irradiations. Proton irradiation also resulted in increases in a' precipitate size and Cr content, but at a slower rate than with electrons due to the influence of ballistic dissolution. Self-ion irradiations caused a reduction in the size and Cr content of a' with dose, and above a threshold damage rate of 1-3 x 10(-4) dpa/s, the precipitates were completely dissolved. The ballistic dissolution parameter for self-ion irradiations calculated from both the Nelson-Hudson-Mazey model and a mixing model was in the range 2-5 x 10(20) atoms/m2?dpa compared to a value of -9 x 10(19) atoms/m(2)?dpa for proton irradiation, and explains the different behaviors of the precipitates for these two irradiating particles. Overall, it was found that cascade size strongly determines the stability of a' precipitates and damage rate has its major impact on the rate at which a' precipitates grow or dissolve.

Automated summary

Samples of a Fe-15Cr model alloy were irradiated with different particles to study the stability of a' precipitates. Results showed that electron and proton irradiation increased the size and Cr content of a' precipitates, but at different rates due to the influence of ballistic dissolution. Self-ion irradiation caused a reduction in the size and Cr content of a' precipitates, and above a certain damage rate, the precipitates were completely dissolved. Cascade size strongly determines the stability of a' precipitates, while damage rate affects their growth and dissolution rate.