Tensile properties and microstructure of helium implanted EUROFER ODS

Helium effects on creep properties of Fe–14CrWTi ODS steel at 650 °C

“…When a bubble reaches this size it will further grow continuously. However, there are investigations over a wide temperature range which show that there is no HTHE in martensitic stainless steels [26,27], although helium bubbles are formed, grow and transfer into voids in the interior and at the boundaries of grains in such materials [9,28,29]. Up to now, only a tentative explanation of this different behaviour of austenitic and ferritic/ martensitic materials is given in terms of the more complex microstructure of the latter.…”

He-Cavity Accumulation at Oxide Particle-Matrix Interface in Ni-Base ODS Superalloy

“…The average diameter of oxide particle is 9.0 nm for as-received condition, 15 nm for irradiated specimen at 1000 C for 50.9 dpa and about 14 nm after equivalent annealing at 1000 C for 10 h. The number of measured oxide particles is 990 for (b), 250 for (c), but we cannot know (a) s number from Ref. 7). Note that from Figs.…”

“…In eqs. (6) and (7), assuming that S varies from 5 to 10 for the present ion irradiation, Table 1 shows the value of m * He and r * c when the sample is irradiated at 600 C and 1000 C. We also estimated the real values of m He using the amount of the injected He and calculated r C from the TEM images, the mean size and the number density of the cavities obtained by the present and the past examinations 8) , and these values are listed in Table 1. According to Table 1, it is clear that the values of m He and r c exceeds the critical values of m * He and r * c at both temperatures.…”

“…To overcome these problem, we have studied oxide particle dispersion strengthened (ODS) Ni-based alloy 6) . ODS method is well-known in the Febased ODS steels for the eld of fusion reactor materials which suppress the He accumulation at grain-boundaries by trapping He cavities at the interface between nely dispersed oxide particles and matrix 7) . In this work, we evaluate the ability of oxide particles to trap the He cavities in Ni-based ODS alloy, using a Fe/He dual-ion bombardment simulation technique for neutron irradiation.…”

Positron Annihilation Doppler Broadening Study of the Helium-implanted (ODS) EUROFER

“…While the size of the bubbles seems to generally increase with temperature, the number density of the bubbles varies, depending on the actual temperature range and/or the irradiation dose respectively. Many recent studies reported a saturation or even decrease of the number density of growing helium bubbles at high irradiation temperatures (high dpa) [4,5]. This points to a coalescence of large open-volume defects, a mechanism which has been suggested for the third stage of the evolution of positron lifetime reported in [2].…”