Molybdenum rhenium alloys are primary candidates for structural components in space nuclear reactors. However, their degradation mechanisms under the combined influence of irradiation, temperature, and mechanical stress remain poorly understood. In this study, 240 MeV argon ions were used to generate a damage layer of approximately 23 & micro;m in a Mo-14Re alloy, with doses ranging from 1.25 to 10 dpa. Microstructural characterization using GIXRD and TEM revealed significant lattice expansion, reaching a maximum swelling of 0.956% at 3.75 dpa, and a high density of dislocation loops. These microstructural changes resulted in pronounced hardening. Crucially, this study demonstrates that the macroscopic performance degradation is not merely a result of thermal creep in the bulk material but is significantly accelerated by the premature cracking of the brittle surface layer. These surface cracks act as geometric notches that induce severe stress concentrations and propagate into the substrate. This failure mechanism, characterized by damage propagation from the surface to the interior, provides a critical new perspective for evaluating the irradiation tolerance and service life of refractory alloys.

Molybdenum rhenium alloy is considered a key candidate material for space nuclear reactors due to its excellent high-temperature properties, mechanical properties and radiation resistance. In this study, 300MeV Xe26+ ions were used to generate a damage layer of approximately 12µm in a Mo-14Re alloy at 500 °C, with irradiation doses of 0.5dpa, 2.5dpa and 3.1dpa. And the evolution of their microstructure and changes in their mechanical properties were investigated. Observing changes on the surface and fracture surface morphology of the samples using a scanning electron microscope (SEM), X-ray diffraction (XRD) and nanoindentation were used on crystal structure, hardness before and after irradiation. High-temperature creep tests were conducted on samples under different radiation doses, and different stress with high irradiation doses. The results show that: After irradiation at high dose of 2.5dpa, pores appear on the surface of the samples. The hardness of the alloy increased steadily with increasing dose, exhibiting typical radiation hardening. Furthermore, the intrinsic hardness H₀ obtained from the Nix-Gao model fits increased from 3.61GPa in the unirradiated state to 5.32GPa at 3.1dpa, confirming the effect of irradiation-induced hardening. As the irradiation dose increases, the creep life of the sample gradually decreases. This study reveals the performance degradation mechanism of the Mo-14Re alloy after irradiation, providing a reference for the application evaluation of such alloys in extreme environments like nuclear reactors.

The deuterium (D) retention in reduced-activation ferritic/martensitic (RAFM) steels under simultaneous hydrogen (H) and D plasma exposure was investigated, with a focus on the coupling effects of pre-existing displacement damage. Controlled damage profiles were introduced via heavy-ion irradiation using 4.5 MeV and 387 MeV Fe ions. The results indicate that heavy-ion irradiation significantly enhances D retention and induce high-temperature desorption above 1000 K. Crucially, the co-introduction of H effectively suppresses D retention, especially in the high-temperature regime. These findings imply that in a D-tritium (T) fusion environment, the co-existence of multiple hydrogen isotopes may naturally mitigate T retention, offering positive implications for T management and safety in future fusion reactors.

The deuterium (D) retention in reduced-activation ferritic/martensitic (RAFM) steels under simultaneous hydrogen (H) and D plasma exposure was investigated, with a focus on the coupling effects of pre-existing displacement damage. Controlled damage profiles were introduced via heavy-ion irradiation using 4.5 MeV and 387 MeV Fe ions. The results indicate that heavy-ion irradiation significantly enhances D retention and induce high-temperature desorption above 1000 K. Crucially, the co-introduction of H effectively suppresses D retention, especially in the high-temperature regime. These findings imply that in a D-tritium (T) fusion environment, the co-existence of multiple hydrogen isotopes may naturally mitigate T retention, offering positive implications for T management and safety in future fusion reactors.

This study aims to explore the role of entropy in the radiation resistance of high-entropy pyrochlores by combining experimental results and theoretical calculations. A carefully designed compositional strategy was crucial for reducing the impact of element differences on the radiation resistance of pyrochlore. This approach enabled the acquisition of direct experimental results regarding the influence of entropy on radiation performance. The high-entropy pyrochlores were irradiated with high-energy (352.8 MeV) Fe ions to evaluate their radiation resistance. The results indicate that as entropy increases, the sensitivity of high-entropy pyrochlores to amorphization decreases. Bader charge analysis reveals that increasing entropy at the A-site significantly alters the bonding environment of A-site cations and reduces the covalency of the bond. Further calculations of cation antisite defect formation energy indicate that increasing entropy lowers the defect formation energy. These findings provide new insights for the potential application of high entropy materials in extreme environments.

The Nano-indentation deformation behavior of the heavy ion irradiated RAFMs is investigated in the present work. Specimens of the CLF-1 steel were irradiated with 123.4 MeV 20Ne ion at both -50 °C and 400 °C, respectively, to achieve a mean displacement damage level of 0.15 dpa. A quasi-uniform distribution of the displacement damage was produced in the specimens by utilizing an energy degrader at the irradiation chamber. The results of nano-indentation experiments indicate that during the loading stage, the irradiated materials exhibit a lower strain rate, but during the holding stage after reaching the maximum load, the irradiated materials show a higher strain rate than the un-irradiated material. Transmission electron microscopy observation showed that the low-temperature irradiation produced a high density of irradiation-induced dislocation loops, which impeded the glide of dislocation lines during the loading stage. However, as the load increases gradually to the holding stage, the dislocation lines can overcome the pinning by the dislocation loops. The strain that did not occur due to the pinned effect of the dislocation loops in the loading stage was released during the holding stage, resulting in a higher strain rate in the irradiated specimen during the holding stage. Based on the Peierls mechanism, a quantitative relationship between the number density of the irradiation-induced dislocation loops and the strain rate during the holding stage was established. The calculated results agree well with the experimentally obtained strain rate during the holding stage.

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Gas-filled bubbles present significant challenges in materials as they make materials porous and weaken the strength of materials. Here, argon bubbles that are formed during the fabrication of oxide dispersion strengthened (ODS) steels are investigated. The Ar bubbles are attached to nano-oxides which are dispersed in the matrix. MA956 ODS specimen was irradiated with 362 MeV 129Xe26+ at room temperature to about 7 dpa at peak damage. The behavior of Ar bubbles in different irradiation depths was investigated by using transmission electron microscopy (TEM) via cross-section specimens. The results show that Ar-bubbles in the peak damage and ions deposition region experience an apparent dissolution. Further, we simulate the behavior of isolated Ar bubble and attached Ar bubble to oxide under primary knock-on atoms (PKA) with different energy and numbers by using molecular dynamics (MD). The results show that high energy PKA (exceeding 30 keV) and multiple cascades can contribute to the effective ejection of Ar atoms from bubbles. Meanwhile, the interface between oxide and bubble contributes less to the bubble dissolution. Besides that, the effects of thermal ejection and excess self-interstitial atoms generated from the implantation of foreign atoms on the dissolution of Ar bubbles are discussed.

The present study aimed to investigate the mechanical property of heavy ions irradiated Reduced Activation Ferrite/Martensitic (RAFM) steels. The CLF-1 steel was irradiated by 33.5 MeV Fe ions at room temperature, resulting a peak displacement damage of 20 displacements per atom (dpa). Experimental analysis was conducted using Electron Backscatter Diffraction (EBSD) mapping-assisted Focused Ion Beam (FIB) technique to prepare micro-pillars oriented along crystal directions <0 0 1>. Subsequently, these fabricated micro-pillars underwent compression tests utilizing a flat indenter within the Nano-indentation setup. Engineering Stress-strain curves were generated for specimens both un-irradiated and irradiated. The yield strength of the un-irradiated and irradiated specimens in the <0 0 1> directions was determined by using the engineering stress-strain curves. In addition, the critical resolved shear stress (CRSS) of the un-irradiated and irradiated specimens was calculated. Microstructural analysis revealed that the formation of dense and fine dislocation loops were appeared in the material after irradiation. By combining the results of microstructure analysis with the dispersion barrier hardening model, the changes in CRSS caused by irradiation were calculated. Furthermore, the number of dislocation lines participating in deformation at a strain of 20 % was quantified, with the irradiated specimen exhibiting an increase of 33 % in comparison to the un-irradiated specimen.

依托兰州重离子研究装置(HIRFL),开展了3种不同氧化物弥散强化的16Cr-ODS铁素体钢的重离子辐照损伤研究,旨在探究氧化物颗粒结构参数(尺寸和密度)对材料辐照硬化和Ne离子辐照脆化效应的影响.采用6.17 MeV/u的Ni离子辐照和Ne离子,借助辐照终端的梯度减能装置在材料样品中产生了均匀的辐照损伤坪区.借助纳米压痕和小冲杆测试技术分别获得了辐照前后材料的纳米硬度和延伸率数据.探究了氧化物纳米颗粒的界面对于缺陷的的吸收尾闾(sink strength)和材料的辐照硬化/脆化的关系.结果表明,吸收尾闾越大,ODS钢的抗辐照硬化和脆化能力越强.

In the present work, irradiation hardening of a low-copper reactor pressure vessel steel (Chinese A508-3) is studied. Specimens of the RPV steel were irradiated with high-energy Fe ions at a terminal of a cyclotron at a low temperature around 173 K to two damage levels of 0.15 and 0.21 dpa. Micro Vickers hardness was measured from the specimens after stepwise thermal annealing at temperatures of 300, 573, 623 and 673 K, respectively. The specimens irradiated to both two doses exhibit obvious hardening. With the increase of the annealing temperature, the irradiation hardening decreases monotonically. Fitting of the Arrhenius plots gives an apparent activation energy of 0.10 +/- 0.01 eV for the temperature regime from 573 to 673 K. Positron annihilation lifetime spectrometry (PALS) tests revealed that the average positron annihilation lifetime initially decreases significantly with the increase of annealing temperature due to defect recombination, then increases at temperatures above 573 K due to vacancy agglomeration. Dislocation loops in a high density were observed in the irradiated specimens after annealed at 673 K, and are regarded to be the main reason for the irradiated hardening. Assuming the evolution of the dislocation loops is controlled by the migration and coalescence process of self-interstitial-atom clusters (SIA-clusters) produced in cascade damage, an activation energy E-m (0.55 +/- 0.05 eV) was deduced for the migration of SIA clusters in the irradiated steel specimens.

Pure V and V–5Cr–5Ti were irradiated by He and high-energy heavy ions to various doses. Nanoindentation was used to characterize the hardness change induced by ion irradiation. Under high-energy heavy ions irradiation, the hardness of pure V increased rapidly and saturated at very low damage level (0.03 dpa), the hardness of V–5Cr–5Ti increased slowly and tended to saturate at the damage higher than 0.4 dpa. In contrast to high-energy heavy-ion irradiation, more significant hardening occurred in both pure V and V–5Cr–5Ti under He ion irradiation. The significant hardening induced by He ion irradiation at the low dose was probably from the coarsening of dislocation loops due to the existence of He atoms in materials. TEM results revealed that He bubbles with high density have been formed in V–5Cr–5Ti at the high dose. The estimation based on the dispersion barrier hardening model suggested that He bubbles exhibited as weak obstacles due to the limitation of size, the major contribution to hardening was considered to be from dislocation loops.

使用拉曼光谱和透射电镜等分析手段研究了高能快重离子辐照对ZnO单晶内部结构特性的影响。结果表明,经过快重离子辐照后,在ZnO单晶的拉曼光谱中出现了两个新的振动吸收峰。采用不同轴向的拉曼入射光表征方法,证实了位于576 cm-1的振动吸收峰与氧空缺位（V0）密切相关。经离子辐照后透射电镜图像显示出现了许多间隙原子、空位和位错等缺陷,而电子衍射图表明试样没有出现明显的非晶化。这个结果表明,较高的能量和辐照剂量对氧化锌的整体结构和性能几乎没有影响,也充分证明ZnO单晶具有良好的抗辐照性能。

A damage plateau (4000 appm/0.25 dpa) was produced in T92 and MA956 by multi-energy He ion irradiation. Nanoindentation was used to characterize the irradiation hardening effect. For the pristine samples, the hardness at the region shallower than 200 nm deviated evidently from the relation predicted by the Nix-Gao model. The hardness of the damaged layer produced by ion irradiation also located in this region. Therefore, a modified model by introducing a maximum allowable density of GNDs proposed by Ruiz-Moreno was used to analyze the hardness data. The fitted result indicated that the hardness of the damaged layer was overestimated by 28.5% for T92 and 48.4% for MA956 in contrast to that obtained from the Nix-Gao model, and a hardening fraction of 64.5% for MA956 and 103.6% for T92 was also obtained. A lower hardening fraction of MA956 was considered to be related to the existence of oxide particles in the matrix.

Annealing behavior of the hardening and ductility loss of an oxide-dispersion-strengthened (ODS) ferritic steel (16Cr-4Al) irradiated with high-energy heavy ions is studied. Ne-20 ions with 123.4 MeV supplied by a cyclotron was used to produce a quasi-uniform atomic region of atomic displacement damage and Ne concentration from surface to a depth of 33 mu m in the specimens. Two atomic displacement levels (0.16dpa, 0.70dpa) were approached at about 220 K. The irradiated specimens were subsequently thermally annealed at room temperature, 473 K and 673 K, respectively. Hardness and ductility of the specimens were investigated with nano-indentation technique and small-punch test. The data of the nano hardness were fitted by Nix-Gao model to obtain the bulk equivalent hardness values. The irradiated specimens show observable hardening, which recedes monotonously with the increase of annealing temperature. The Arrhenius plots show a good linearity in the entire temperature range investigated, with an apparent activation energy of 0.13 +/- 0.01 eV for both the two damage levels. Assuming that the hardening is caused by the self-interstitial-atom (SIA) clusters initially produced by the cascade damage, an activation energy of 0.70 +/- 0.05 eV is deduced for the migration and coalescence process of the SIA-clusters. The small punch test (SPT) of the high-dose specimens shows that a minor ductility loss occurred under conditions as-irradiated or subsequently thermally annealed at 473 K, while a remarkable increase of the ductility loss was observed after the thermal annealing at 673 K, which coincides with the formation of nano-scale gas bubbles in high density in the specimen. It is indicated that the formation of bubbles has minor on the irradiation hardening. A comparison of three ODS ferritic steels Ne-ion-irradiated to 0.7 dpa/260 appm(Ne) shows that the ductility loss decreases with the increase of the sink strength of the oxide dispersoids/ferritic substrate interfaces. (C) 2020 Elsevier B.V. All rights reserved.

In the present work, irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1 candidate to fusion reactor blankets is studied. Specimens were irradiated with high-energy 14N and 56Fe ions at a terminal of a cyclotron to three successively increasing damage levels of 0.05, 0.1 and 0.2 dpa at about -50 oC. Energy of the incident ions was dispersed to successively decreasing 11 grades by using an energy degrader, thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25 μm, which is sufficiently broad for the Vickers hardness test. Eight different loads (i.e. 98 mN, 196 mN, 490 mN, 980 mN, 1.96 N, 4.9 N, 9.8 N and 19.6 N) were performed on the specimens to obtain the depth profiles of the Vickers hardness by using a micro-hardness tester. Hardening was observable at the lowest damage level, and increases with the increase of irradiation dose. A power law correlation of the Vickers hardness with the damage level (HV0=1.49+0.76dpa0.31) is proposed. Test with nano-indentation technique was also performed, and a linear relationship between the Vickers micro-hardness and the nano-hardness (HV0=0.83H0) was observed. A comparison with other RAFM steels (CLAM, JLF-1, F82H, EUROFER97 etc.) under neutron or charged particle irradiation conditions show that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of the irradiation hardening. The difference of the irradiation hardening may be attributed to difference in prior-irradiation microstructures.

Multiple-energy He ions were used to produce thicker damage layers with 3000 appm/0.17 dpa (by low dose implantation) and 6000 appm/0.34 dpa (by high dose implantation), respectively, in mono-crystalline 4H-SiC at room temperature (RT). Results from XRD and nano-indentation tests indicated that the low dose implanted sample contained larger numbers of defects, but still sustained crystalline state. However, amorphization occurred in the sample with high implantation dose. Subsequently, both implanted samples were annealed in vacuum condition at 300, 500, 700, 900 and 1100 degrees C for 0.5 h, successively. After each step of annealing, the samples were characterized by Raman spectroscopy. Raman spectra indicated that graphite was formed in the implanted samples. From RT to 500 degrees C, the concentration of graphite in both implanted samples increased with temperature, which was considered to be related with the release of He atoms from the Si tetrahedral interstitial sites. However, the graphite showed different annealing behavior for the low dose and high dose implanted samples at the temperature from 500 to 1100 degrees C. For the sample with low implantation dose, the graphite concentration decreased with increase of temperature, which was due to the decomposition of the distorted graphite. However, for the sample with high implantation dose, the graphite completely vanished after annealing at 700 degrees C, which could be caused by the occurrence of recrystallization in SiC.

In this paper, third generation SiC fiber material irradiated with the 410 MeV energy of [Formula: see text] ion at 173 K was analyzed by Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscope (TEM). Raman spectroscopy, TEM and XRD data show modifications in the local structure of irradiated SiC fibers. Although highly disordered SiC grains were observed in appearance, no evidence of amorphization was found. After the Sn ions irradiation and XRD, two diffraction peaks disappeared, which showed that the rich Si and C could be further combined in [Formula: see text] ions/cm 2 dose irradiation condition. This result mainly explains the electron damage and the nuclear damage process in SiC fibers, leading to the recombination or migration of defects.

SrLaAlO4 materials irradiated with 350 MeV Fe-56(21+) ions have been studied by Raman spectroscopy, Potoluminescence (PL) spectra and X-ray diffraction (XRD). A wide luminous band appeared after Fe-56(21+) irons irradiation; and it increase with irradiation dose. The PL peaks intensity of SrLaAlO4 crystal increased rapidly; and the peaks intensity reached the maximum threshold dose at 5 x 10(10) ions/cm(2). A series of relatively sharp emission peaks are caused by the transition from E-2(g) to (4)A(2g) at the spectrum of 1.82eV-2.14eV. In the oxide fluorescent material, the high level excitation transitions ( (4)A(2g ->) T-2(2g)) are parity and spin forbidden. The peaks caused by the (4)A(2g) -> T-2(2g) transitions is not clearly observed in many fluoride phosphors; while, after high-energy (56)Fe(21+ )ion irradiation, the parity and spin-forbidden transitions have been observed at 2.25eV-2.48eV. It was found that the spin forbidden transition was allowed to somewhat extent due to the lattice vibration; and, the spin orbital coupling caused by mixing (4)A(2), E-2, T-2(2) and T-4(2) states.

The Ordovician intraoceanic Macquarie Arc terrane is faulted against coeval, quartz‐rich turbidites of the Adaminaby Group within the Lachlan Orogen of eastern Australia. Debates exist concerning the polarity of subduction beneath the Macquarie Arc and the nature of its emplacement, given it is juxtaposed against the Adaminaby Group to both the west and east. We present new provenance and zircon analyses of the Triangle Formation, which consists of interleaved quartz‐rich passive margin sandstones and island arc volcaniclastic rocks. In contrast, the structurally underlying Adaminaby Group contains no volcaniclastic detritus and displays a strong passive margin affinity. One sample from the Triangle Formation yielded a youngest zircon age of 456 ± 16 Ma indicating a subtle Macquarie Arc signature among an overwhelmingly Neoproterozoic and older Gondwanan provenance. The Adaminaby Group yielded a youngest zircon age of 481 ± 6 Ma and a strong Gondwanan zircon signature. We compared these results with volcaniclastic rocks from the Weemalla Formation stratigraphically higher in the Macquarie Arc, which yielded a distinctly unimodal zircon age of 451 ± 8 Ma, which is indistinguishable from the youngest zircon in the Triangle Formation. We suggest the Triangle Formation represents trench fill material sourced predominantly from the Gondwana margin but including some younger Macquarie Arc detritus. This constrains the initiation of this arc‐continent collision to between 448 and 462 Ma (Late Ordovician).