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The materials employed in the present experiment were a new F/M steel-SIMP designed by Institute of Modern Physics(IMP) and Institute of Metal Research(IMR), Chinese Academy of Sciences(CAS), and two kinds of ODS steels, namely commercial MA956 and Eurofer-ODS steels. Detailed thermal treatment and chemical composition for each type of steel are summarized in Table 1. It is worth further clarification that, as a new type of domestic independently developed martensitic steel, SIMP steel has better oxidation resistance and liquid metal corrosion resistance than other traditional F/M steels with the high content of Si. Moreover, the low activation characteristics of SIMP steel are realized via replacing both Mo with W and Nb with Ta.
Steels Fe Cr C Mn S W V Ta Si P Y2O3 Ni Al Ti Mo SIMP#1 Bal 10.24 0.22 0.52 0.0043 1.45 0.18 0.12 1.22 0.004 Eurofer-ODS#2 Bal 8.70 0.11 0.44 0.004 1.00 0.19 0.10 0.30 MA956#3 Bal 19.93 0.023 0.09 0.008 0.008 0.006 0.51 0.04 4.75 0.39 0.02 #1 SIMP: normalized at 1 040 °C for 30 min and tempering at 760 °C for 90 min.
#2 Eurofer-ODS: normalized at 1 150 °C for 60 min, tempering at 750 °C for 120 min.
#3MA956: canned and extruded at 1 100 °C, hot-rolled for 240 min, reheating to 1 100 °C for 30 min, hot-rolled.Table 1. Details of chemical composition of SIMP, Eurofer-ODS, and MA956 steels (%).
The samples used for the ions implantation were cut into dimensions of 3 mm×3 mm×1 mm with diamond wire cutting machine. One surface of each sample was ground into smooth surface with gradually refined sandpaper from 600 to 2 500 grades, and then was polished to a mirror-like surface by using vibration polisher.
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The implantation experiment was conducted in the Low Energy heavy ion Accelerator Facility(LEAF) at IMP, CAS. All of the materials were injected by 2 MeV He ions to a fluence of 1×1017 ions/cm2 at 500 and 600 °C. The detailed implantation parameters are shown in Table 2. The implantation temperature with a fluctuation of about
$ \pm $ 5 °C was monitored by two thermocouples near the sample. The current intensity was measured by two Faraday tubes in real time and remained at 30 μA.Sample Ion Energy/
MeVTem/℃ Fluences/
(ions·cm−2)SIMP/EU-ODS/MA956 He 2 500 1×1017 600 Table 2. Detailed parameters of He ions implantation experiment.
The depth distribution of both radiation damage level and He ions deposition concentration are obtained by SRIM 2013 calculations in “quick Kinchin-Pease calculation” mode[8]. During SRIM calculation, the density of target materials is 7.87 g/cm3, and the displacement threshold energies of both Fe and Cr are set as 40 eV[9].
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The cross-sectional TEM slices with thickness of about 70 nm were prepared by dual beams focused-ion beam(FIB) lift-out method. The microstructures were observed under the bright field image model of FEI Tecnai F20 TEM operated at 200 kV.
Irradiation induced swelling for a selected region can be calculated by Eq. (1):
where V is the volume of the selected region after irradiation. ∆V represents the relative change of the volume caused by bubbles in the region, that is the total volume of the bubbles in this region.
Effect of Nanostructures on Bubbles Nucleation and Growth in F/M and ODS Steels Exposed with High Helium Fluence
doi: 10.11804/NuclPhysRev.39.2021030
- Received Date: 2021-03-25
- Rev Recd Date: 2021-04-22
- Publish Date: 2022-03-01
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Key words:
- nanostructure /
- steel /
- He bubble /
- nucleation and growth /
- TEM
Abstract: A new type of F/M steel (SIMP steel) and two kinds of ODS steels (MA956 and Eurofer-ODS steels) were irradiated by 2 MeV He ions to fluence of 1×1017 ions/cm2 at 500 and 600 °C. After irradiation, swelling behaviors and effect of nanostructures (such as grain boundaries, precipitates and nano-oxide particles) on the nucleation and growth of He bubbles were studied by transmission electron microscope. The results show that both SIMP and Eurofer-ODS steels exhibit better swelling resistance than MA956 ODS steel at 500 °C, because the grain boundaries or precipitates pronouncedly inhibit the growth of He bubbles. The Eurofer-ODS steel shows best swelling resistance due to the inhibition of He bubbles growth by the grain boundary and oxide interface at 600 °C. The present work shows that nanostructures in materials inhibit the process of He bubble growth under high He fluence conditions, but the degree of inhibition varies with different materials.
Citation: | Jing LI, Peng JIN, Minghuan CUI, Yabin ZHU, Chao LIU, Krsjak Vladimir, Kongfang WEI, Lilong PANG, Yanbin SHENG, Tielong SHEN, Zhiguang WANG. Effect of Nanostructures on Bubbles Nucleation and Growth in F/M and ODS Steels Exposed with High Helium Fluence[J]. Nuclear Physics Review, 2022, 39(1): 101-107. doi: 10.11804/NuclPhysRev.39.2021030 |