Excellent Irradiation Resistance Research Articles

Molecular dynamics simulations on the evolution of irradiation-induced dislocation loops in FeCoNiCrCu high-entropy alloy

High-entropy alloys (HEAs) have received extensive attention due to their excellent irradiation resistance. In this work, the displacement cascade simulations were performed by using the molecular dynamics (MD) method to study the dislocation loop evolution in FeCoNiCrCu HEA. The simulation results showed the dislocation loops evolution in pure Ni were dominated by Frank loops with larger size but lower density, which was caused by the absorption of prismatic dislocation loops by Frank loops. In contrast, prismatic dislocation loops were more prevailing in FeCoNiCrCu HEA with smaller size but higher density, since the interactions between dislocation loops were suppressed in HEA. To figure out the influence of HEA on dislocation loop evolution, the formation energy, interaction energy and mobility were analyzed. It was found that formation energy and interaction energy were basically the same, while the mobility of prismatic dislocation loop in HEA was much lower than that in pure Ni, which was considered as the main reason why the irradiation-induced dislocation loops were more difficult to interact and grow in HEA. The current work provides new insights into understanding the irradiation resistance from micro-mechanism in FeCoNiCrCu HEAs.

Microstructural Evolution and High‐Temperature Tensile Properties of 15Cr‐Reduced Activation Ferritic Steel Processed by Hot Powder Forging of Mechanically Alloyed Powders

Reduced activation ferritic steels are being explored as possible cladding tube materials for nuclear reactors because of their low activation and excellent irradiation resistance. In the current investigation, reduced activation ferritic steel (Fe–15Cr–2W) is processed by mechanical alloying of elemental powders followed by hot powder forging. Mechanical alloying is carried out in a Simoloyer attritor mill (Zoz GmbH), after which the powders are placed in a mild steel can and forged at 1200 °C in H2 atmosphere. X‐ray diffraction and transmission electron microscopy (TEM) investigation reveal that 10 h of mechanical alloying is required to achieve complete dissolution of Cr and W in the Fe matrix powder. The relative density and hardness distribution of the forged slab is evaluated in longitudinal as well as transverse direction to optimize the powder forging operation. Electron backscatter diffraction analysis showed dynamic recrystallization to take place during the course of hot powder forging. Tensile tests are performed at room temperature as well as at elevated temperatures (600 and 700 °C). The yield strength and ultimate tensile strength at room temperature as well as at elevated temperatures are found to be higher than those reported in literature for reduced activation ferritic steels consolidated by other techniques.

Atomistic simulation of chemical short-range order on the irradiation resistance of HfNbTaTiZr high entropy alloy

High entropy alloys (HEAs) have been considered as one of the potential structural material candidates for fourth-generation nuclear reactors and fusion reactors due to their excellent irradiation resistance. Current studies have shown that the chemical short-range order (CSRO) usually exists in HEAs, which has a significant effect on the mechanical properties and irradiation resistance of HEAs. Refractory high entropy alloys (RHEAs), as a new class of HEAs have better mechanical properties at high temperatures than face-centered cubic (FCC) HEAs, and therefore have better prospects of application in the nuclear field. In this study, CSRO and its effect on the irradiation resistance of HfNbTaTiZr are analyzed via molecular dynamics (MD) and Monte Carlo (MC). The primary cascade simulations, multi-cascade simulations and surface bombardment simulations are carried out to simulate the generation and accumulation of irradiation damage. The results of the primary cascade simulations and surface bombardment simulations of CSRO models show that the presence of CSRO induces cascade splitting into subcascades. The presence of subcascades reduces the thermal peak enhancement effect and thus lowers the recombination rate of Frenkel pairs (FPs) in the damage zone when FPs concentrations are low. However, the creation of subcascades increases the size of the damage zone caused by the cascade. Thus, when the concentrations of FPs are high, the larger area of damage zone allows more of the already existing FPs to be included, thus promoting their recombination, i.e., impedes their accumulation when concentrations are high. These subcascades lower the recombination of FPs at low FPs concentrations but inhibit their accumulation at high FPs concentrations. The presence of CSRO is also beneficial in inhibiting the growth of point defect clusters, which further improves the resistance of HfNbTaTiZr to dislocation generation. Furthermore, the presence of CSRO facilitates the irradiation-induced phase transition. But it is found that HfNbTaTiZr shows suppression of HCP cluster growth. And the tendency to break down large HCP clusters into smaller ones is demonstrated in the CSRO model. From our calculations we also find that the irradiation-induced HCP atoms have a higher potential energy relative to the matrix. The potential energy difference between those energetic HCP atoms and the matrix can lead to generating a great number of insurmountable barriers pervading the matrix and largely suppressing the long-term mobility of FPs, thus limiting their aggregation and growth into clusters.

Study on the Irradiation Evolution and Radiation Resistance of PdTi Alloys.

Medium-entropy alloys (MEAs) exhibit exceptional mechanical properties, thermal properties, and irradiation resistance, making them promising candidates for aerospace and nuclear applications. This study utilized molecular dynamics simulations to examine the defect behavior in PdTi alloys under various irradiation conditions. Simulations were performed using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) with the modified embedded-atom method (MEAM) potential to describe interatomic interactions. Various temperatures, primary knock-on atom (PKA) energies, and elemental ratios were tested to understand the formation and evolution of defects. The results show that compared to pure Pd, PdTi alloys with increased entropy exhibit significantly enhanced irradiation resistance at higher temperatures and PKA energies. This study explored the impact of different elemental ratios, including Pd, PdTi1.5, PdTi, and Pd1.5Ti. Findings indicate that increasing the Pd concentration enhances the alloy's irradiation resistance, improving mobility and recombination rates of defect clusters. A one-to-one Pd-to-Ti ratio demonstrated optimal performance. Temperature analysis revealed that at 300 K and 600 K, PdTi alloys exhibit excellent irradiation resistance at a PKA energy of 30 keV. However, as the temperature rises to 900 K, the irradiation resistance decreases slightly, and at 1200 K, the performance is likely to decline further. This study offers some useful insights into the irradiation evolution and radiation resistance of PdTi medium-entropy alloys, which may help inform their potential applications in the nuclear field and contribute to the further development of MEAs in this area.

Fabrication of highly thermally conductive and irradiation resistant UHMWPE-based composites for nuclear shielding applications

With the advancement of nuclear energy, the safety of both humans and the surrounding environment necessitates the adoption of effective nuclear radiation shielding materials. Polymer-based shielding materials have garnered attention due to their lightweightness and ease of moldability. However, they normally possess low thermal conductivity (λ) and easy deformation at high temperatures, which potentially cause catastrophic disasters during service if they are mechanically failed due to heat accumulation. To address the above concerns, highly thermally conductive and irradiation resistant ultra-high molecular weight polyethylene (UHMWPE)-based composites were fabricated. Planar fillers such as boron nitride (BN) and graphite (Gt) along with lead (Pb) powders were employed to construct a densely packed filler network for improving the λ and mechanical properties of UHMWPE-based composites. The λ was increased from 3.81 to 6.20 W/mK when 20 wt% Pb (2.88 vol%) was added to BN30/Gt20 (i.e., UHMWPE composite with 30 wt% BN and 20 wt% Gt), representing an increase of 62.73 %. Moreover, the λ of Pb80 was increased from 0.87 to 3.29 W/mK by merely adding 5 wt% (9.99 vol%) Gt, representing a remarkable increase of 278.16 %. GEANT4 simulation results indicated that BN30/Gt20/Pb20 exhibited excellent neutron shielding performance. Samples which were irradiated using 60Co γ-rays at a total dosage of 1.15×105 Gy exhibited enhanced mechanical performance, which indicated excellent irradiation resistance of UHMWPE-based composites. Therefore, a facile method was proposed to prepare multi-functional UHMWPE-based composites that demonstrate promising application in nuclear sectors.

Enhancing strength and irradiation tolerance of Mg alloy via co-addition of Mn and Ca elements

The Mg alloys with combination of high strength and excellent irradiation resistance are currently required for research reactors. In this work, the novel Mg-3Mn-0.5Ca alloy with a high strength of over 300 MPa has been fabricated via co-addition of Mn and Ca elements. Moreover, the Xe ion implantation (300 °C/4.5 × 1015 ions/cm2) is conducted for pure Mg, Mg-3Mn and Mg-3Mn-0.5Ca alloys. Microstructure characterization shows that the number density of dislocation loops is comparable between Mg-3Mn and pure Mg, while the phase boundary of nano-Mn particles could act as the sink to absorb more Xe atoms, resulting in the abundant formation of Xe bubbles in the matrix of irradiated Mg-3Mn alloy. With further minor addition of Ca element, the formation of Xe bubbles and dislocation loops in Mg-3Mn-0.5Ca alloy has been obviously suppressed, and the abundant grain boundaries (GBs) due to grain refinement then act as the sink region for Xe precipitation. The limited number density of Xe bubbles leads to the extremely low swelling ratio in Mg-3Mn-0.5Ca alloy, ∼0.08 %. The result above suggests that the Mn and Ca co-addition could enhance the mechanical properties and irradiation tolerance of Mg alloys, simultaneously. The present low-alloying strategy would provide a new design reference for novel nuclear materials.

Large-size CsI:Na single crystals for future high energy physics experiment

With the development of deep space exploration, nuclear medical imaging, high-energy physics experiments, and other fields, the demand for large-size CsI:Na crystals is increasing due to the low cost of use, high light yield, and excellent irradiation resistance of CsI:Na crystals. In this work, we investigated the scintillation characteristics of thirty-five Ø76 mm × 76 mm CsI:Na single crystals, delving into the variation of energy resolution and light yield. Meanwhile, a method based on 137Cs source collimation and coupling the crystal to PMT in different directions was used to reveal the uniformity of scintillation performance of large-size CsI:Na single crystals. The Bridgman-grown 51 mm × 51 mm × 152 mm CsI:Na single crystals have an energy resolution of 6.5 % at 662 keV, which does not change significantly regardless of irradiation location or irradiation method.

Irradiation response of microstructure and mechanical properties of NbMoVCr multi-principal element alloy coatings

In this study, NbMoVCr multi-principal element alloy (MPEA) coatings with near-equal atomic ratios were deposited onto the ferritic/martensitic (F/M) steel substrate by magnetron sputtering and then irradiated using 6 MeV Au2+ at room temperature (RT) and 550 °C, respectively. The results demonstrate that the NbMoVCr coatings have excellent irradiation resistance in terms of phase stability. RT-irradiation introduces both interstitial- and vacancy-type dislocation loops, and the dislocation loop density increases with the increase of irradiation damage dose. Meanwhile, RT-irradiation could also induce grain growth of the coating. However, under high-temperature irradiation, more recombination and annihilation of irradiation-induced defects, and recrystallization occur in the coating. In addition, irradiation also promotes the desegregation of V and Cr elements at the grain boundaries and enhances the uniformity of the distribution of coating elements. Irradiation softening and hardening in NbMoVCr coatings are also found to depend strongly on both irradiation damage dose and irradiation temperature. The creep deformation mechanism of the coating is dominated by diffusion; thus, the irradiation-enhanced diffusion reduces the creep resistance of the coating.

Wearable electronic device for X-ray warning and health monitoring

The well-developed multifunctional wearable electronic device has fed the demand for human medicine and health monitoring in complex situations. However, the advancement of nuclear technology, especially irradiation medicine and safety inspections, has increased the exposure risk of irradiation safety workers. Traditional irradiation detectors are stiff and incompatible with the skin, and lack human health monitoring function, thus it’s vital to apply these flexible sensors for irradiation warning. Here, we report a novel composite gel device synthesized through solution processes by combining the Cs3Cu2I5:Zn nano-scintillator with the pre-patterned biocompatible gel, exhibiting a bi-functional response to motion/vibration sensing and sensitive irradiation warning. These wearable devices achieve a pressure sensitivity of up to 34 kPa−1 in a low-pressure range (0–3 kPa), a low limit of detection (LoD) down to 1.4 Pa, enabling health monitoring functions of pulse monitoring, finger bending, and elbow bending. Simultaneously, the device scintillates under X-ray irradiation among a wide dose rate range of 54–1167 μGyair s−1. The robust device shows no obvious signal loss after 4000 compression cycles and also excellent irradiation resistance over 50 days, broadening the path for designing and realizing new functional wearable devices.

Enhanced irradiation tolerance of the body-centered cubic structured FeCrW medium-entropy alloy as revealed from primary damage process

Multi-principal element alloys have attracted much attention in the development of nuclear reactor materials due to their potentially excellent irradiation resistance. Here, we employed Molecular Dynamics (MD) simulations to investigate displacement cascades resulting from Primary Knock-on Atoms (PKA) energies ranging from 10 to 50 keV in body-centered cubic structured FeCrW, FeCr and α-Fe. The analysis encompasses irradiation-induced defect generation and evolution, aiming to elucidate mechanism of irradiation tolerance. The simulations results indicate that FeCrW medium-entropy alloys generate more Frenkel defects during the thermal spike stage compared to α-Fe, yet fewer residual defects are observed in FeCrW at the end of the cascade. The suppression of the increase in defects number in FeCrW compared to α-Fe is significantly enhanced with the increasing PKA energies. It is foreseeable that the number of residual defects in FeCrW will be much smaller than that of α-Fe with a dramatic increase of PKA energy, which will be attributed to the improved defect self-self-healing ability in FeCrW. Moreover, the mechanism of enhanced defect self-self-healing is attributed to the size of the defect cluster, the formation and distribution of defects, the enhanced thermal spike, and the chemical disorder caused by the increase in composition leading to low thermal conductivity. The spectral energy density (SED) curves spikes of α-Fe, FeCr and FeCrW reveal an important role in the enhanced phonon scattering in improving defect self-repairing ability due to chemical disorder. Our research provides valuable insights for guiding the development of advanced multi-principal element alloy structural materials in nuclear industry, particularly for the fourth-generation fast reactor.

Flexible Solid-Electrolyte-Gated-Dielectric Carbon Nanotube Thin Film Transistors and Integrated Circuits with the Recorded Radiation Tolerance and Reparability.

Radiation-tolerance and repairable flexible transistors and integrated circuits (ICs) with low power consumption have become hot topics due to their wide applications in outer space, nuclear power plants, and X-ray imaging. Here, we designed and developed novel flexible semiconducting single-walled carbon nanotube (sc-SWCNT) thin-film transistors (TFTs) and ICs. Sc-SWCNT solid-electrolyte-gate dielectric (SEGD) TFTs showcase symmetric ambipolar characteristics with flat-band voltages (VFB) of ∼0 V, high ION/IOFF ratios (>105), and the recorded irradiation resistance (up to 22 Mrad). Moreover, flexible sc-SWCNT ICs, including CMOS-like inverters and NAND and NOR logic gates, have excellent operating characteristics with low power consumption (≤8.4 pW) and excellent irradiation resistance. Significantly, sc-SWCNT SEGD TFTs and ICs after radiation with a total irradiation dose (TID) ≥ 11 Mrad can be repaired after thermal heating at 100 °C. These outstanding characteristics are attributed to the designed device structures and key core materials including SEGD and sc-SWCNT.

Properties of radiation-induced point defects in austenitic steels: a molecular dynamics study

Austenitic steels are recognized as excellent structural materials for pressurized water reactors due to their outstanding mechanical properties and radiation resistance. However, compared to the widely studied FeCrNi series of steels, little is known about the radiation resistance of FeCrNiMn steel. In this study, the generation and evolution of radiation-induced defects in FeCrNiMn steel were investigated by molecular dynamics simulations. The results showed that more defect atoms were produced in the thermal spike stage, but fewer defects survived at the end of the cascades in FeCrNiMn compared to pure Fe. Point defect properties were analyzed by molecular statics, and the formation energies of defects in FeCrNiMn were lower than those of pure Fe, while the migration energies were higher. Compared to FeCrNi, FeCrNiMn had smaller migration energies and a larger overlap of vacancy and interstitial migration energies. The low vacancy formation energies and widely overlapping migration energies suggested that the number of point defects in the thermal spike stage was higher, but the possibility of recombination was greater. Additionally, Mn exhibited the smallest interstitial formation energies and migration energies. The difference in defect migration energies revealed that vacancy and interstitial defects migrate through different alloy constituent elements. This study revealed the underlying mechanism for the excellent irradiation resistance of FeCrNiMn.

Superior radiation resistance of ODS-RAFM steels revealed by Positron annihilation spectroscopy study

Oxide-dispersion-strengthened (ODS) reduced-activation ferritic/martensitic (RAFM) steels are considered as most promising structural materials for fusion reactors and other advanced nuclear systems due to its excellent irradiation resistance under high dose irradiations. However, the extreme complex synergistic effect between transmuted helium/hydrogen and displacement damage which most seriously affects the structure and mechanical properties of ODS-RAFM steels is very difficult to understand, especially the role of hydrogen still remains unclear. Taking advantage of very sensitive to small vacancy clusters of Positron annihilation spectroscopy (PAS) method, we conducted irradiation defect study on ODS-RAFM, RAFM and its corresponding model alloy Fe–9Cr and α-Fe to investigate their anti-swelling properties at the early stage of irradiation with hydrogen-helium synergism and the mechanism. Three distinct irradiation schemes including (1) single Fe ion beam, (2) simultaneous Fe and He (named Fe + He) ion beam, (3) subsequent H ion injection after Fe + He (named Fe + He/H) ion beam irradiation were performed. Hydrogen-helium synergistic effects on vacancy evolution within these steels were explored combining the first-principles calculation. The implantation of He was observed to significantly increase defect concentration among all four steels, while H exhibited interestingly complexity on affecting the evolution of helium bubbles. The H post-injection increased defect concentration obviously in the materials with abundant sinks, but improved poorly in ones with rare sinks. Through the systematic study of the interactions between H, He, and vacancies, it was revealed that even at the early irradiation stage, ODS-RAFM steels has already exhibited excellent irradiation resistance compared to other alloys across three irradiation schemes.

A Review of Irradiation-Tolerant Refractory High-Entropy Alloys

Along with the globalization of environmental problems and the rapid development of the field of nuclear technologies, the severe irradiation damage of materials has become a big issue, restricting the development of advanced nuclear reactor systems. Refractory high-entropy alloys (RHEAs) have the characteristics of a complex composition, a short-range order, and lattice distortion and possess a high phase stability, outstanding mechanical properties, and excellent irradiation resistance at elevated temperatures; thus, they are expected to be promising candidates for advanced nuclear reactors. This review summarizes the design, preparation, and irradiation resistance of irradiation-tolerant RHEAs. It encompasses a comprehensive analysis of various aspects, including the evolution of defects, changes in microstructure, and the degradation in properties. Furthermore, the challenges and insufficiently researched areas regarding these alloys are identified and discussed. Building on this foundation, the review also provides a forward-looking perspective, outlining potential avenues for future research.

Influence of metal electrodes on the irradiation resistance of HZO ferroelectric thin film capacitors and mechanism analysis

In application scenarios such as astronautics, high-altitude aircraft, medical radiography, high-energy physics, and nuclear power plants, the irradiation resistance of electronic components is one of the basic requirements for their reliability. HfO2-based ferroelectric films have the advantages of high CMOS process compatibility, good miniaturizability, low operating voltage, and excellent irradiation resistance, which are the core materials for the new generation of irradiation resistance ferroelectric memories. In this paper, two kinds of metal-electrode ferroelectric capacitors, W/Hf0.5Zr0.5O2/W (WW) and Pt/Hf0.5Zr0.5O2/Pt (PP), have been prepared, and three gradient γ-irradiation experiments have been carried out on the two kinds of ferroelectric capacitors. The effect of metal electrodes on the irradiation resistance of Hf0.5Zr0.5O2 ferroelectric thin films was carefully investigated by comparing and analyzing the statistical laws of polarization change and rectangularity change before and after irradiation of a large number of devices. The experimental results show that the WW devices have better irradiation resistance than PP devices, and we further explain the irradiation resistance mechanism by first-principle calculations and finite element analysis to verify the credibility of the experimental results. Finally, we conducted a comparative test of the fatigue and wake-up characteristics of the WW devices before and after irradiation, and the results show that the prepared W/Hf0.5Zr0.5O2/W devices can withstand very high total γ-dose radiation, reaching up to 13.86 Mrad(Si), and they are very suitable for the application of irradiation resistant electronics.

Integration fabrication of polyimide composite films for aerospace applications

AbstractPolyimides externally deployed in spacecraft or satellites extensively have various aerospace hazards, including atomic oxygen (AO) erosion, irradiation degradation, and electrostatic charge/discharge (ESC/ESD). To cope with these challenges, we fabricate a ZnO/CuNi‐polyimide composite film with augmented permanence. Using spectroscopy and microscopy techniques, we have shown that the combination of chelation and cross‐linking in the interfacial architecture leads to enhanced interfacial compatibility and mechanical robustness. Besides, due to the positive AO diffusion barrier ability of the wurtzite ZnO, our composite film shows remarkable AO resistance and a very small Ey value of 6.88 × 10−26 cm3/atom, which is merely 2.29% of that of pristine polyimide. Moreover, the well‐defined nanocrystalline state with minimal lattice swelling (0.3%–0.7%) of the Fe+‐irradiated ZnO/CuNi‐polyimide at a damaging dose of 353.4 dpa demonstrates its excellent irradiation resistance. Finally, the ZnO/CuNi‐polyimide also shows sufficient electrostatic dissipation capacity to cope with the ESC/ESD events. Our fabrication approach for composite films based on multi‐technology integration shows potential for aerospace applications and deployment.

Interactions between displacement cascades and grain boundaries in NiFe single-phase concentrated solid solution alloys

Single-phase concentrated solid solution alloys (SP-CSAs) are promising structural materials with excellent irradiation resistance. It is very important for their application in nuclear reactor structures to understand the interactions between their grain boundaries (GBs) and irradiation-induced defects. With molecular dynamics (MD) simulations, the displacement cascades in NiFe SP-CSAs with Σ5(210) symmetrical tilt GB were studied. Compared with pure Ni, NiFe has higher sink strength of GB for vacancies but has little effect on the interstitial absorption of GB. The formation energies of interstitials and vacancies near the GB are more dispersed, so that the point defects are more difficult to aggregate, which is beneficial for the recombination of interstitials and vacancies near the GB. Both the formation energies of point defects and the sink strengths of GB for point defects could be changed with the SP-CSA compositions. When the Fe atom concentration is higher than 30 at.%, the point defects are easier to annihilate. Both the effects of the PKA energy and the PKA-GB distance on the displacement cascades damage can be explained with the size of overlapping region between the cascade region and GB. In addition, the formation of SP-CSAs helps to annihilate the vacancies in NiFe with Σ37(750) symmetrical tilt GB and Σ5 twist GB.

Synthesis of Amorphous Poly (aryl ether ketone) Resin and its Anti‐Irradiation Properties under Gamma Ray

AbstractThe stability of polymer materials used in nuclear environment directly determines the life and reliability of nuclear power equipment. Poly (aryl ether ketone) (PAEK) itself exhibits excellent irradiation resistance which can be widely used. The emphasis of this study lies in designing and synthesizing three different structures of amorphous PAEKs by the solution SN2 nucleophilic polycondensation. The thermodynamic properties and structural changes of the materials under gamma‐ ray (γ‐ray) irradiation were investigated and the irradiation‐resistance mechanism was discussed. The present results illustrate that the performance can be basically stable lower than 108 Gy. Up to 1013 Gy dose, γ‐ray has little effect on the impact resistance and Young ′s modulus of the three materials, the tensile strength and elongation at break decreased with the increase of irradiation dose. No new structures were formed after irradiation, and all the three materials decomposed slightly caused by oxidized.

Reduced He ion irradiation damage in ZrC-based high-entropy ceramics

Excellent irradiation resistance is the basic property of nuclear materials to keep nuclear safety. The high-entropy design has great potential to improve the irradiation resistance of the nuclear materials, which has been proven in alloys. However, whether or not high entropy can also improve the irradiation resistance of ceramics, especially the mechanism therein still needs to be uncovered. In this work, the irradiation and helium (He) behaviors of zirconium carbide (ZrC)-based high-entropy ceramics (HECs), i.e., (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C, were investigated and compared with those of ZrC under 540 keV He ion irradiation with a dose of 1×10¹⁷ cm⁻² at room temperature and subsequent annealing. Both ZrC and (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C maintain lattice integrity after irradiation, while the irradiation-induced lattice expansion is smaller in (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C (0.78%) with highly thermodynamic stability than that in ZrC (0.91%). After annealing at 800 ℃, ZrC exhibits the residual 0.20% lattice expansion, while (Zr_0.2Ti_0.2Nb_0.2Ta_0.2W_0.2)C shows only 0.10%. Full recovery of the lattice parameter (<i>a</i>) is achieved for both ceramics after annealing at 1500 ℃. In addition, the high entropy in the meantime brings about the favorable structural evolution phenomena including smaller He bubbles that are evenly distributed without abnormal coarsening or aggregation, segregation, and shorter and sparser dislocation. The excellent irradiation resistance is related to the high-entropy-induced phase stability, sluggish diffusion of defects, and stress dispersion along with the production of vacancies by valence compensation. The present study indicates a high potential of high-entropy carbides in irradiation resistance applications.

Unique dislocation loops distribution of AlCrFeNiTix eutectic high-entropy alloys under high-temperature ion irradiation

Eutectic high-entropy alloys (EHEAs) have drawn great attention due to their excellent high-temperature mechanical properties. A group of EHEAs AlCrFeNiTix with different titanium contents was irradiated with 3 MeV Fe11+ ions at 500 °C with fluences of 9.1 × 1014 and 4.55 × 1015 ions/cm2. The disordered body-centered-cubic (BCC, A2) exhibited smaller-sized dislocation loops than those of ordered BCC (B2) based on Transmission electron microscopy (TEM) analysis. The type of loops found in AlCrFeNi alloy were<100>and 1/2<111>. The fraction of 1/2<111>was higher, indicating the excellent irradiation resistance of EHEAs. Small size and large density of dislocation loops formed after the addition of Ti. Phase boundaries in the alloys could effectively decrease the density and size of dislocation loops because of defects annihilation at phase boundaries. In combination with density function theory (DFT) results. B2 phase exhibited better energy landscape advantage in the Ti accommodating, and the MSD results indicated that the lattice distortion effect caused by Ti entering B2 phase was more obvious than A2 according to the density function theory (DFT) results. Our research exhibited a beneficial scheme for solid solution strengthening of elements in EHEAs, and provided an insight into the suppression of dislocation loops under irradiation.