In-situ TEM study of microstructural evolution in NFA and Cr3C2@SiC-NFA composite during ion irradiation

In this work, the ion irradiation responses of a Fe-based nanostructured ferritic alloy or NFA (Fe9Cr2W0.2V-0.4Ti-0.3Y(2)O(3)) and a Cr3C2@SiC-NFA composite were assessed. In-situ ion irradiation with TEM observation was carried out by using 1 MeV Kr++ ions at doses of 0, 1, 3, 5, 10 dpa and temperatures of 300 degrees C and 450 degrees C. Both the NFA and Cr3C2@SiC-NFA samples showed significant dislocation density after 10 dpa at 300 degrees C. However, the Cr3C2@SiC-NFA composite showed a significantly lower dislocation loop density and a smaller average loop size during the irradiation at 450 degrees C as opposed to the NFA. At 300 degrees C, 1/2 < 111 > type dislocation loops were observed in both the NFA and Cr3C2@SiC-NFA samples. Interestingly, at 450 degrees C, < 100 > type loops were dominant in the NFA sample while 1/2 < 111 > type loops were still dominant in the Cr3C2@SiC-NFA sample. The results were discussed based on the large surface sink effects and enhanced interstitial-vacancy recombination at higher temperatures. The additional Si element in the Cr3C2@SiC-NFA sample might have played a significant role in determining the dominant loop types.