VOID SWELLING IN BINARY FE-CR ALLOYS AT 200 DPA

Microstructural examinations have been performed on a series of binary Fe-Cr alloys irradiated in the FFTF/MOTA at 425 degrees C to 200 dpa. The data represent the highest swelling levels reported to date in ne utron-irradiated ferritic alloys. The alloy compositions ranged from 3 to 18% Cr in 3% Cr increments and the irradiation temperature corresp onded to the peak swelling condition for this alloy class. Density mea surements showed swelling levels as high as 7.4%, with the highest swe lling found in the Fe-9Cr and -6Cr alloys. Microstructural examination s revealed that the highest swelling conditions contained well-develop ed voids, often as large as 100 nm, and a dislocation network comprise d of both a/2[111] and a[100] Burgers vectors. Swelling was lower in t he other alloys, and the swelling reduction could be correlated with i ncreased precipitation. These results are considered in light of the c urrent theories for low swelling in ferritic alloys, but no theory is found to completely explain the results.