Microstructural Evolution of Fe-Cr-W Model Alloys During Fe^+ Ion Irradiation

The effect of radiation on microstructural evolution and phase transformation in Fe-50Cr-5W and Fe-50Cr-8W model alloys was examined. The 300keV Fe + ion irradiation was performed at temperatures of 550, 600, 670, and 700°C at a rate of 1.4 × 10 18 ions/m 2 s for (1.2-1.8) x 10 3 s in a transmission electron microscope (TEM). The damage peak level corresponded to about 190-285 dpa. The peak depth positions of damage and Fe + ion were about 60 and 100 nm, respectively. Dislocation loops were observed in the Fe-50Cr-W alloys up to 700°C. A Laves phase of tens of nanometers in size was formed in the Fe-50Cr-W alloys within a few minutes, but the formation of Laves phase decreased with increasing irradiation temperature. Sigma-phase grains of about 50-100 nm in size and micro-crystallines were observed in the alloys irradiated at 670 and 700°C. However, in the specimen aged at 700°C for 1000 h and the one aged at 700°C for 10 h after 80% CW, only the Laves phase had formed and no sigma phase was observed in the Fe-50Cr-W alloys. These results indicate that Fe + ion irradiation can strongly influence the Laves and sigma phase transformations, and microstructural development, in the Fe-50Cr-W alloys.