FACTORS WHICH CONTROL THE SWELLING OF FE-CR-NI TERNARY AUSTENITIC ALLOYS

In agreement with limited earlier studies, a comprehensive irradiation experiment conducted in both EBR-II and FFTF demonstrates that while cold-working usually decreases void swelling of ternary Fe-Cr-Ni alloy s at relatively low irradiation temperatures, it in general increases swelling at higher irradiation temperatures, Aging of cold-worked spec imens to produce cellular dislocation networks tends to further increa se swelling, especially at higher nickel levels. The swelling of terna ry alloys at lower nickel levels also appears to be sensitive to detai ls of the preirradiation annealing treatment. The differences in the d etails of reactor operating conditions also exert an influence on void nucleation and thereby on the duration of the transient regime of swe lling. In the current irradiation series this leads to the swelling de veloped in EBR-II at similar to 30 dpa being consistently larger than that in FFTF. All of these results confirm an earlier conclusion that the primary variability of void swelling of FeCrNi alloys lies in the incubation and transient regimes, rather than in the steady-state swel ling rate regime. Under certain conditions, the transient regime can b e made to approach 0 dpa.