Influence of variable temperatures irradiation on microstructural evolution in phosphorus doped Fe–Cr–Ni alloys

To evaluate the influence of temperature change on microstructural evolution in phosphorus modified Fe–Cr–Ni alloys, irradiations at 473/923, 673/923, 773/923 K were performed on a Fe–16Cr–17Ni–0.1P alloy with 2.4 MeV Cu ions. In these experiments, specimen temperature was changed in a stepwise manner during the irradiation. In the case of 673/923 K-irradiation, the phosphide density after the second irradiation at 923 K was about 2 orders of magnitude higher than that in the constant temperature irradiation at 923 K. The influence of the first irradiation at lower temperature remained to a higher dose level of 75 dpa. High void swelling of about 12% was observed after varying temperature irradiation. In the constant temperature irradiation, on the other hand, void swelling was strongly suppressed. The influence of the first irradiation was relatively small in 473/923 K-irradiation. Defect clusters formed during the first irradiation at 473 K disappeared during temperature elevation up to 923 K, and the microstructural evolution during the second irradiation at 923 K was similar to that in the constant temperature irradiation.