This study investigates the influence of nanoscale oxide dispersoid characteristics on irradiation hardening in FeCrAl-based oxide dispersion strengthened (ODS) ferritic steels. Four ODS alloys with systematically varied oxide size and number density-achieved through Al and Zr additions-along with a conventional HT9 steel, were irradiated with Fe-56 ions to 0.8 dpa at 563 K. Vickers micro-hardness tests revealed that the Zr-added and Al-free ODS steels exhibited significantly lower irradiation hardening than their Al-containing counterparts, while HT9 showed the highest hardening. This enhanced radiation tolerance is attributed to the high number density of fine (similar to 2-10 nm) oxide particles, which act as efficient sinks for point defects, suppressing dislocation loop formation. A power-law correlation was established between the oxide-related sink strength and the irradiation-induced hardness increment. The improved irradiation resistance is primarily attributed to the increased sink strength. Assuming interstitial-type dislocation loops govern hardening, the dispersed barrier hardening (DBH) model yielded predictions consistent with experimental data, confirming the critical role of microstructure in defect mitigation.

The precipitation of solutes is the primary factor that leads to the occurrence of irradiation hardening and embrittlement, thus limiting the service life of reactor pressure vessel (RPV) steels. In this study, four model alloys (Fe-1.35Mn-0.75Ni, Fe-1.35Mn-0.20Si, Fe-0.75Ni-0.20Si and Fe-1.35Mn-0.75Ni-0.20Si) were used to investigate the influence of solute elements on grain size, hardness, irradiation hardening, and defect clustering behavior. The materials were irradiated with 3.5 MeV Fe ions to doses of 0.1, 0.3, 1.0, and 3.0 dpa at 290 degrees C. Results indicated that the addition of solute Mn resulted in grain refinement while the addition of solutes Ni and Si led to grain coarsening. The strength of the model alloys was affected by the change in grain size. A definite dose rate effect was found in all four model alloys under irradiation, where irradiation with a higher dose rate led to a lower irradiation hardening effect and irradiation with a lower dose rate induced a higher hardening effect. Atom probe tomography (APT) results revealed that the precipitated solutes were always coupled with interstitial defect clusters. Solute Mn had a strong influence on cluster nucleation and a weak influence on cluster size. Solutes Si and Ni significantly promoted the nucleation and growth of clusters, and Ni had a greater influence on the nucleation and growth of clusters than Si. Meanwhile, solute Si consistently exhibited a low fraction in the clusters when the solute Mn element was presented in the alloys.

目的 研究在563 K的温度条件下,高能重离子辐照导致国产RPV钢A508-3的硬化行为.方法 使用回旋加速器提供的352.8 MeV Fe21+对A508-3钢试样进行辐照,使其依次达到0.15、0.30、1.50 dpa的损伤水平.借助辐照终端的梯度减能装置,在样品表面至25μm的深度范围内产生一个准均匀分布的原子离位损伤坪区,并使用纳米压痕仪和维氏显微硬度计测量了试样的硬度.结果 考虑到压痕尺寸效应的影响,采用Nix-Gao模型对硬度数据进行拟合,由于高能Fe离子产生了较厚的损伤区,辐照试样中的软基效应明显减弱.辐照后的试样出现明显的硬化现象,且随着辐照剂量的增大,硬化增量有饱和趋势.通过辐照前和辐照至0.15 dpa试样的微硬度数据,得出其与纳米硬度之间的线性关系(Hv0=0.85 H0).结论 借助A508-3辐照前后的硬度数据,计算发现试样的屈服强度增量与辐照剂量之间存在一种幂函数关系,这为A508-3钢中子-离子辐照硬化的映射关系研究提供了基础数据.

目的 采用小冲杆测试方法测量高能重离子辐照反应堆压力容器A508-3钢的辐照硬化和脆化特性,为工况条件下反应堆压力容器寿命预测提供实验依据.方法 采用兰州重离子加速器提供的高能C6+离子通过减能装置在290℃条件下开展A508-3钢辐照实验,并在样品表面形成一定厚度、准均匀分布的离位损伤层.通过开展不同辐照剂量辐照样品的小冲杆测试,得到不同辐照剂量A508-3钢的小冲杆载荷-位移曲线.通过对小冲杆测试得到的载荷-位移曲线的分析,测定不同辐照剂量样品的辐照硬化和脆化特性.结果 压力容器A508-3钢辐照样品的硬化和脆化随着辐照剂量的增加逐渐增强,0.15 dpa以前呈线性增长,而后缓慢增大,约0.2 dpa时达到饱和趋势.结论 通过小冲杆测试可以得到离子辐照样品的硬化和脆化行为,A508-3钢辐照硬化和脆化行为具有一致的变化趋势.

FeCrAl oxide dispersion strengthened (ODS) steel is regarded as one of the most promising candidate materials for nuclear fission reactors such as supercritical pressurized water reactor (SCPWR), sodium-cooled fast reactor (SFR), and lead bismuth-cooled fast reactor (LFR) and so on, since it has excellent irradiation resistance and good corrosion resistance of super-critical water and Pb-Bi coolants. In the present work, irradiation response of a Zradded FeCrAl ODS steel (15Cr-4Al-0.1Ti-0.6Zr) together with an Al-free ODS (16Cr-0.1Ti) steel and a non-ODS steel T91 was studied. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the microstructures including grains, dislocations, and oxides in the pristine specimens and irradiation defects in the irradiated specimens. Nano-indentation tests were used to evaluate the change in hardness after irradiation. The oxides in the 15Cr-4Al-0.1Ti-0.6Zr specimen are slightly larger than those in the 16Cr-0.1Ti specimen, but with a similar number density. After irradiated with 9.45 MeV Bi-83(35+) to 26 dpa at ambient temperature, hardening was observed in all the specimens. Irradiation hardening of the 15Cr-4Al-0.1Ti-0.6Zr specimen is slightly higher than the 16Cr-0.1Ti specimen but significantly lower than the non-ODS steel T91. The irradiation defects in the ODS steel specimens are apparently smaller than those in T91 with a similar number density. By calculating sink strength of the initial microstructures such as grains, dislocations and oxides, the evolution of irradiation defects was discussed. A linear relationship between the irradiation hardening and the sink strength was established. A similar linear relationship between the calculated irradiation hardening using the TEM data (based on dispersion barrier hardening model (DBH) and Friedel-Kroupa-Hirsch (FKH) model, respectively) and sink strength was also found. The calculated irradiation hardening is relatively lower than the experimental value, indicating the possible contribution of Cr segregation to hardening which needs further study.

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.

Heavy-ion irradiation has been widely used to simulate neutrons-irradiation induced damage effects, due to its higher damage rate and lower activation of the post-irradiation manipulation. The high-energy ion beam is capable of producing a thickness of dozens of microns damaged region in steel, making it possible to evaluate the macroscopic mechanical properties of the irradiated specimens. In the present paper, a method to quantify the constitutive relationships of high-energy heavy-ion irradiated steels is proposed. Ni22+ ions with a kinetic energy of 357.86 MeV provided by a cyclotron were used to produce a quasi-homogeneous atomic displacement damaged layer (about 25 mm in thickness) in specimens of 316 L stainless steel. The temperature of the specimens were kept at about -50 degrees C during ion irradiation. Two damage levels of 0.16 and 0.33 displacement per atom (dpa) were approached. Small punch test of the unirradiated and irradiated phi 3 mm disk samples was carried out to obtain the load-deflection curves. A series of finite element simulation of SPT of the laminated irradiated samples, in combination with sequential programming algorithm, was performed to characterize the constitutive relationships of the irradiation damaged layer of the samples. Finite element simulations with obtained constitutive relationships show agreement with the experimental results. Nanoindentation tests were carried out to verify the identified constitutive relationships. The nanoindentation results show an irradiation induced hardening in good agreement with that from the obtained constitutive relationships. (C) 2020 Elsevier B.V. All rights reserved.

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.

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.

Microstructure damage and evolution in 4H-SiC under He-ion implantation and post-annealing have been investigated by the combination of fourier transform infrared spectrometer (FTIR), Raman scattering spectroscopy and high resolution X-ray diffractometer (HRXRD). After implantation, the 4H-SiC specimen exhibits a heavy damage and some amorphous state appear. With increasing annealing temperature, to some extent recovery in damaged lattices was observed, as a result of the peaks of Raman and HRXRD regain their intensities. However, the reverse annealing behavior in damaged peaks was displayed after annealed at 973K. This reverse annealing effect was revealed to be due to the formation and the growth of He bubbles above 973K.

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.

The small scale specimen techniques have been a fast-growing research field for the past three decades. Small punch test is the most commonly used small specimen test technology and numerous mechanical properties are obtained from the test. Due to the highly complex stress state of the sample during the experimental process, many empirical formulas are used to obtain mechanical properties of the specimen. The curve obtained by finite element modelling of the small punch test is quite different from that obtained from the experiment, this paper present a systematic study on the problem. A revised model is proposed to solve the issue and we conclude that the rod must be modelled in the finite element simulation and the deformation of the rod is the causes of the misaligned.

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.

ZnO single crystal materials irradiated with 200 MeV energy 86Kr17+ ions have been analyzed by a series of theoretical calculations, Raman spectroscopy and TEM tests, etc. After irradiation by 200 MeV 86Kr17+ ions, two broad vibrational absorption peaks appeared and there is no obvious change in other characteristic peaks. By measuring the Raman spectra of the incident light perpendicular to and parallel to the z axis of the crystal, it was proved that the vibration absorption peak of 526 cm−1 ∼ 600 cm−1 is caused by defects related to oxygen vacancy (VO). The experimental data fully proved that ZnO single crystal has good radiation resistance. These data are of great significance for the application of ZnO materials in various new devices in the future.

Single crystal 6H-SiC was irradiated by inert gas ions (He, Ne, Kr and Xe ions) to various damage levels at room temperature. Nano-indentation test was performed to investigate the hardness change behavior with damage. The depth profile of nano-hardness for 6H-SiC decreased with increasing depth for both the pristine and irradiated samples, which was known as indentation size effect (ISE). Nix-Gao model was proposed to determine an asymptotic value of nano-hardness by taking account of ISE for both the pristine and irradiated samples. In this study, nano-hardness of the irradiated samples showed a strong dependence on damage level and showed a weak dependence on ions species. From the dependence of hardness on damage, it was found that the change of hardness demonstrated three distinguishable stages with damage: (I) The hardness increased with damage from 0 to 0.2 dpa and achieved a maximum of hardening fraction similar to 20% at 0.2 dpa. The increase of hardness in this damage range was contributed to defects produced by ion irradiation, which can be described well by Taylor relation. (II) The hardness reduced rapidly with large decrement in the damage range from 0.2 to 0.5 dpa, which was considered to be from the covalent bond breaking. (III) The hardness reduced with small decrement in the damage range from 0.5 to 2.2 dpa, which was induced by extension of the amorphous layer around damage peak.

Metallic nanoparticle (NP) shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an amorphous matrix. We investigate the shape deformation of Ag NPs with irradiation fluence, and 357 MeV Ni ions are used to irradiate the silica containing Ag NPs, which are prepared by ion implantation and vacuum annealing. The UV-vis results show that the surface plasmon resonance (SPR) peak from Ag NPs shifts from 400 to 377 nm. The SPR peak has a significant shift at fluence lower than 1 × 1014 ions/cm2 and shows less shift at fluence higher than 1 × 1014 ions/cm2. The TEM results reveal that the shapes of Ag NPs also show significant deformation at fluence lower than 1 × 1014 ions/cm2 and show less deformation at fluence higher than 1 × 1014 ions/cm2. The blue shift of the SPR peak is considered to be the consequence of defect production and Ag NP shape deformation. Based on the thermal spike model calculation, the temperature of the silica surrounding Ag particles first increases rapidly, then the region of Ag NPs close to the interface of Ag/silica is gradually heated. Therefore, the driven force of Ag NPs deformation is considered as the volume expansion of the first heated silica layer surrounding Ag NPs.