Fission-fusion correlations for swelling and microstructure in stainless steels: Effect of the helium to displacement per atom ratio

Abstract

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Helium bubble nucleation and growth in alloy HT9 through the use of in situ TEM: Sequential he-implantation and heavy-ion irradiation versus dual-beam irradiation

“…Based on our observations, two observations can be made: (i) as the dose and helium concentration increases the density of cavities increases; and (ii) as the He appm/dpa increases the bubble size gets smaller; indeed, at the low He appm/dpa ratio, bubbles did not become visible until doses greater than 26 dpa with 57.2 appm He whereas for the larger appm/dpa ratio, there is sufficient helium to stabilize the vacancies and grow into visible bubbles at a lower dose. These two trends are supported by other studies of dual-beam experiments [26,27,30].…”

“…This being said, in our case, our experiments were done at the same temperature with samples of about the same thickness, so it is reasonable to assume that such depleted zone would be of similar thickness for each sample so that the trends registered within our experiments are reliable from that prospect. The same trend was reported in other alloys including austenitic alloys such 316 SS [27,28]. In [28] Katoh et al compared different He appm/dpa rates up to 25 dpa at a temperature of 873 K, using 4 MeV Ni 3+ and 1 MeV He 2+ ions in AISI 316 bulk samples.…”

Microstructural evolution in an austenitic stainless steel fusion reactor first wall

“…The predictions were made for an increased He/dpa ratio of 10 appm He/dpa. The most systematically observed trend in the literature on helium effects is that higher He/dpa ratios promote cavity formation (34,35). The effect can be approximately described by a simple power dependence of the cavity density, N , on the He/dpa ratio…”

Void-Precipitate Association During Neutron Irradiation of Austenitic Stainless Steel

“…Large voids directly associated with precipitate phase particles have been a prominent feature of the microstructure of neutron irradiated stainless steels since the discovery of voids nearly 20 years ago [1], However, that association did not receive much experimental or theoretical attention until recently [2][3][4][5][6][7][8], Some investigators did single out the phenomenon [9,10] and proposed [9,11] possible mechanisms that would enhance void formation and growth at a precipitate/matrix interface.…”