High Temperature Performance Research Articles

Three-dimensionally ordered macroporous CeZrVOx catalyst with remarkable NH3-SCR performance and SO2 tolerance: Key roles of the morphology and highly dispersed V species

Developing effective low-temperature deNOx catalysts with high activity, SO2 tolerance, and stability is crucial yet challenging. Thus, in this work, CeZrVOx catalyst with a three-dimensional ordered macroporous structure was successfully prepared using the PMMA hard template method, and the catalyst has a macropore diameter of up to 110−140 nm. The modification with highly dispersed V significantly enhances the low-temperature activity and broadens the activity temperature window of the catalyst. This is mainly attributed to the increased number of surface acid sites, as well as the higher proportion of Ce3+ and active surface oxygen species induced by V modification. The V species prepared by this method are highly dispersed on the CeZrOx solid solution and combine with Ce to form CeVO4, which is also an important factor in enhancing catalytic activity. The catalyst does not react with SO2 to produce inactive sulfate species; even the formed cerium sulfate species are beneficial for high-temperature performance. More importantly, due to its unique interconnected three-dimensional ordered structure, the catalyst can significantly inhibit the blockage and coverage of NH4HSO4 on the catalyst, thereby exhibiting remarkable resistance to physical poisoning caused by SO2. Even in high concentrations of sulfur-containing atmospheres, the catalyst still shows high catalytic activity. This work offers meaningful guidance into developing denitration catalysts that show superior performance and robust resistance to both physical and chemical poisoning induced by SO2.

Self-assembled skin-like metamaterials for dual-band camouflage.

Skin-like soft optical metamaterials with broadband modulation have been long pursued for practical applications, such as cloaking and camouflage. Here, we propose a skin-like metamaterial for dual-band camouflage based on unique Au nanoparticles assembled hollow pillars (NPAHP), which are implemented by the bottom-up template-assisted self-assembly processes. This dual-band camouflage realizes simultaneously high visible absorptivity (~0.947) and low infrared emissivity (~0.074/0.045 for mid-/long-wavelength infrared bands), ideal for visible and infrared dual-band camouflage at night or in outer space. In addition, this self-assembled metamaterial, with a micrometer thickness and periodic through-holes, demonstrates superior skin-like attachability and permeability, allowing close attachment to a wide range of surfaces including the human body. Last but not least, benefiting from the extremely low infrared emissivity, the skin-like metamaterial exhibits excellent high-temperature camouflage performance, with radiation temperature reduction from 678 to 353 kelvin. This work provides a new paradigm for skin-like metamaterials with flexible multiband modulation for multiple application scenarios.

Cost-effective strategy for high-temperature energy storage performance of polyimide nanocomposite films

The performance of most polymer-based film capacitors deteriorates severely at high temperatures, while high Tg polymer capacitors, despite their good performance at high temperatures, but their performance still decays severely after prolonged operation at high temperature. This study involves the deposition of a wide bandgap SiO2 inorganic layer on both surfaces of polyimide (PI) films using electron beam thermal evaporation. The findings indicate a substantial enhancement in the breakdown field strength and energy storage density of the composite films at elevated temperature following the deposition of the SiO2 inorganic layer. Specifically, a 100-nm-thick inorganic layer resulted in a breakdown field strength of 459.65 MV m−1 and an energy storage density of 3.2 J cm−3 at 150 °C. Subsequently, the polyimide film coated with a 100 nm SiO2 inorganic layer was infused with small quantities of SrTiO3 nanoparticles, leading to a breakdown field strength of 504.08 MV m−1 and an energy storage density of 6.75 J cm−3 and maintained an efficiency of 90.9 %. These results surpass the performance of the majority of high-temperature polymer films reported to date, with the inorganic layer deposited via electron beam thermal evaporation matching that of the costly magnetron sputtering method. The study presents a cost-effective method suitable for large-scale industrial production, significantly enhancing the electrical performance of PI at elevated temperatures and offering an economical solution for the commercialization of poly composite-based high-temperature capacitors.

Effects of High Al Content on the Phase Constituents and Thermal Properties in NiCoCrAlY Alloys.

MCrAlY (M = Ni and/or Co) metallic coatings are essential for the protection of hot-end components against thermal and corrosion damage. Increasing the Al content is considered a feasible solution to improve the high-temperature performance of MCrAlY coatings. In this paper, the effects of high Al contents (12-20 wt.%) on the phase constituents and cast microstructures in MCrAlY alloys were studied by high-energy X-ray diffraction and electron microscopy techniques combined with phase equilibria calculations. High Al content improved the stability of β, σ, and α phases. Meanwhile, an evolution of the cast microstructure morphology from a dendrite structure to an equiaxed grain structure was observed. The thermal properties were analyzed, which were closely related to the phase constituents and solid-to-solid phase transitions at evaluated temperatures. This work is instructive for developing high-Al-content MCrAlY coatings for next-generation thermal barrier applications.

Microstructure, wear behaviour and laser ablation behaviour of double glow plasma alloyed Ta[sbnd]W coating

TaW alloy is considered a crucial candidate for barrel protective coatings due to its high melting point, excellent high-temperature performance, and ablative resistance. In this study, TaW coating was deposited on the surface of PCrNi3MoVA gun steel by double glow plasma alloying (DGPA) technique. The morphology, phase structure, wear property, and laser ablation behaviour of the TaW deposited coating was studied and analyzed by means of scanning electron microscope (SEM), energy dispersive spectroscopy detector (EDS), X-ray diffractometer (XRD), ball-on-disk friction test, and laser pulse heating experiment. The results showed that the coating was dense and metallurgically bonded to the substrate. The coating was primarily composed of the α-Ta phase, and W was solidly dissolved in the Ta to form a mutual solution with solid-solution strengthening effect. The wear mechanisms of TaW coating were adhesive wear and oxidative wear. During the laser pulse heating (LPH) process, the transition region, center region, and splash region appeared successively in the ablation area of the coating. After 10 s of ablation, only a region with a diameter of 0.1 mm was penetrated, highlighting the effective protective role of the TaW infiltrated layer on the substrate.

Partially solvated cosolvent induced reconfiguration of solvation structure and Helmholtz layer for lithium metal battery

Reconfiguring the electrolyte microstructure containing Li+ solvation structure in bulk electrolyte and Helmholtz layer (HL) near the interface presents a compelling strategy in the design of electrolytes. In this work, ionic liquids (ILs) and partially solvated fluorobenzene (FB) build the unique Li+ coordination state modulated by FB and dominated by anions as well as a HL enriched in non-sacrificial cations on charging. As an important part to regulate the micro environment, FB not only enhances the ion transport kinetics of electrolyte and promotes the interaction of Li+-FSI−, but also participates in constructing a robust solid electrolyte interphase (SEI). Interestingly, FB indirectly promotes the enrichment of ILs’ cations at the HL, which is beneficial for uniform Li metal deposition due to its electrostatic shielding effect. Lithium metal batteries utilizing this electrolyte demonstrate impressive cycling performance at a high rate (approximately 89% capacity retention after 2,500 cycles at 5 C). Furthermore, these cells show excellent high-temperature performance, maintaining 71% of the initial capacity after 1,000 cycles at 70°C and 10 C rate.

Effect of waste cooking oil on the performance of EVA modified asphalt and its mechanism analysis

The balance between the low and high temperature performance of asphalt materials is important to avoid either rutting deformation or low temperature cracking resistance of asphalt pavement. This is beneficial for improving the asphalt pavement comprehensive performance. Considering the excellent high temperature performance of Ethylene–vinyl acetate (EVA) modified asphalt, this study first modified it with Waste Biological Oil (WBO) to prepare WBO/EVA composite modified asphalt (WEMA) with different dosages. Then the samples were evaluated by the traditional physical properties, low and high temperature rheological properties. Finally, the micro mechanism of WBO on EVA modified asphalt were explored by gel permeation chromatography (GPC) test and atomic force microscope (AFM) experiments. The experimental results reveal that WBO has a softening effect on EVA modified asphalt, reducing its stiffness and improving its stretching performance and flowability. In addition, WBO can reduce the high-temperature deformation resistance of EMA modified asphalt, but it significantly enhances the low-temperature property of EVA modified asphalt. When the WBO content ranges from 1.5 to 2.5%, the high-temperature performance of WEMA is inferior to that of EVA-modified asphalt, however, its low-temperature performance is significantly better than that of EVA-modified asphalt. Importantly, within this WBO content range, the comprehensive performance of WEMA is superior to that of pure asphalt. Mechanism investigation showed that WBO reduces the content of macromolecular micelles and average molecular weight in EVA modified asphalt, and it also diluts the asphaltene components in the asphalt system, resulting in a slight weakening of the performance of WEMA at high temperatures and a significant performance enhancement at low temperatures. Ultimately, the utilization of WBO/EVA composite modified asphalt has a better comprehensive performance.

Construction of rGH/NTO 3D-network composite with improved energy release efficiency and significantly reduced corrosiveness of 3-nitro-1,2,4-triazole-5-one

3-Nitro-1,2,4-triazole-5-one (NTO) is a high-energy insensitive explosive with broad application prospects. However, due to the slow energy release kinetics, high decomposition temperature and unsatisfactory safety performance, its effective application is affected. In this paper, a reduced graphene oxide hydrogel (rGH)/NTO composite material was prepared to improve both the physical and chemical properties of NTO. The morphology and structure of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that the rGH/NTO composites did not undergo polymorphic transformation during the preparation process. At the same time, the three-dimensional (3D) network structure formed by rGH can reduce the initial temperature and activation energy of NTO thermal decomposition, and significantly increase the energy release rate. In addition, combined with experiments and DFT theoretical calculations, it is verified that the synergistic effect of the composite material reduces the corrosivity of NTO and increases the insensitivity, thereby improving the effective safety performance. Therefore, the synergistic effect of 3D network structure composite strategy is expected to be extended to the multi-performance control of energetic materials.

Microstructure, property and high-temperature wear performance of Cr3C2-based coatings deposited by conventional and ID-HVAF spray torches: A comparative study

The durability of industrial components exposed to high temperatures can be increased by depositing high-velocity air-fuel (HVAF) sprayed Cr3C2-based coatings. The uniform embedding of wear-resistant Cr3C2 within an oxidation-resistant binder matrix allows HVAF-sprayed Cr3C2-based coatings to be widely used in high-temperature environments. However, consolidating these coatings demands an optimum particle velocity and temperature combination, primarily dependent on the spray torch design. Understanding the role of spray torch variants with altered combustion chamber and nozzle designs is essential, which might influence the coating (splat) formation mechanism and the resultant wear performance. Accordingly, Cr3C2–25NiCr and Cr3C2–30NiCrMoNb were sprayed using different HVAF torches (high-power AK06 and low-power AK05-ID (inner diameter): generate different energy (thermal + kinetic) output) to understand the role of the binder as well as the torch design. The deposited coatings were comprehensively compared based on splat morphology, microstructure, mechanical properties, room and high-temperature erosion and sliding wear behavior. Subsequently, a detailed post-wear analysis was performed to decipher the associated wear mechanism. As inferred from the results, Cr3C2–25NiCr coatings deposited through a high-power AK06 spray torch displayed preferable microstructure, properties and superior wear resistance. The study also offered new insights into HVAF-ID torch-deposited coatings.

Enhanced high-temperature capacitive performance through introduction of polar groups in poly(aryl ether ketone) dielectric polymer

High-temperature poly(aryl ether ketone) dielectrics have attracted application prospects in the field of polymer film capacitors. However, the investigations on improving the capacitive properties of poly(aryl ether ketone) based on molecular structure design strategies were absent. Herein, a series of poly(aryl ether ketone) bearing phthalazinone moiety were synthesized, and the effect of chemical structures on the capacitive properties of the resultant polymers was investigated by experimental data and density functional theory calculation. The introduction of the sulfone group could not only improve the permittivity but also construct deep carrier traps to enhance the breakdown strength, leading to high discharge energy density (Ue) value of the poly(phthalazinone ether sulfone ketone) (PPESK). For the poly(phthalazinone ether nitrile ketone) (PPENK), the introduction of the nitrile group could improve the Ue at room temperature, but reduce the value at elevated temperatures. As a result, at room temperature, the maximum Ue of both the PPESK (4.56 J/cm3) and the PPENK (3.40 J/cm3) was higher than that of the PPEK (3.02 J/cm3). Notably, the maximum Ue of the PPESK reached 3.07 J/cm3 at 150 °C, which is twice that of commercially bi-oriented polypropylene (BOPP) film (1.5 J/cm3 at 70 °C). Additionally, at the electric field of 200 MV/m and 150 °C, the PPESK films exhibited the Ue of 0.72 J/cm3 with charge-discharge efficiency (η) of 97.2 %, which was obviously superior to those of the BOPP (Ue = 0.4 J/cm3 with η of 96 % at 70 °C). This study presents an in-depth analysis regarding the relationship between the sulfone and nitrile groups and the capacitive performance of poly(aryl ether ketone) bearing phthalazinone moiety, which is informative for designing high-temperature dielectric polymers.

High temperature oxidation behavior at 1250 °C: A new multilayer modified silicide coating design strategy on niobium alloys

Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy. However, the long-term protective property of single silicide coating remains a long-time endeavor due to the deficiency of oxygen-consuming phases, as well as the self-healing ability of the protective layer. Herein, a silicide-based composite coating is constructed on niobium alloy by incorporation of nano-SiC particles for enhancing the high-temperature oxidation resistance. Isothermal oxidation results at 1250 °C for 50 h indicate that NbSi2/Nb2O5-SiO2/SiC multilayer coated sample with a low mass gain of 2.49 mg/cm2 shows an improved oxidation resistance compared with NbSi2 coating (6.49 mg/cm2). The enhanced high-temperature antioxidant performance of NbSi2/Nb2O5-SiO2/SiC multilayer coating is mainly attributed to the formation of the protective SiO2 self-healing film and the high-temperature diffusion behavior of NbSi2/substrate.

Laser-induced oxidation of Cf/SiC composites: Oxidation behavior analysis and parameter optimization

Cf/SiC composite is widely utilized in aerospace and defense sectors owing to their outstanding high-temperature and mechanical performance. However, this material is a typical hard-to-machining material. Building upon prior research on the novel laser-induced oxidation-assisted milling technology, this paper conducted an in-depth study of the oxidation of Cf/SiC composite under laser induction. The study combined thermodynamic analysis with the detection of oxidation products to ascertain the oxidation reaction types of Cf/SiC composite. The oxidation process under the induction of lasers with different energy densities was investigated by combining the oxide layer morphology, element distribution, and high-speed photography results. And the oxidation mechanism was elucidated. A second-order response surface model for the oxide layer thickness with respect to the laser energy density, scanning speed, and scanning path spacing was established, and parameter optimization was performed based on this model. Experimental validation demonstrated the reliability of the model predictions.

Comparative analysis of several short-term aging simulation methods and their impact on long-term aging performance of asphalt binders

The aging of the asphalt pavement is an essential factor to consider when constructing a road. Several methods, such as the Thin Film Oven Test (TFOT) and Rolling Thin Film Oven Test (RTFOT), have been used to simulate the short-term aging of asphalt binders. Based on the wide use of polymer-modified asphalt binder and the idea of research facilitation, 5 hours of Pressure Aging Vessel (5 h PAV) was proposed as an alternative to previous short-term aging methods of asphalt binders. However, the efficacy of this technique still needs to be wholly explored in all aspects and requires advanced research. The frequency sweep, temperature sweep, and Multiple Stress Creep Recovery tests were performed to evaluate the high-temperature performance of asphalt binders under aging conditions. In addition, the relaxation test was carried out to determine the low-temperature stress relaxation change and the fatigue cracking resistance of asphalt binders. The Chemical test explored the chemical change of asphalt binders under different aging conditions. The findings revealed that, in the case of neat asphalt binders N50, N70, and N90, the maximum disparity between the aging conditions of TFOT and 5 h PAV was found to be below 6 %. However, the difference between the aging conditions of 5 h PAV and RTFOT was observed to be approximately 20 %. Then, 5 h PAV can be highly recommended as an alternative to replacing TFOT. For SBS and high viscosity-modified asphalt binders HVMA-I and HVMA-II, the maximum gap between 5 h PAV and TFOT was estimated to be approximately 19.71 %. However, the gap between 5 h PAV and RTFOT was estimated to be less than 7 %. Then, 5 h PAV can be an alternative to replace RTFOT for modified asphalt binders if necessary. This study offers a thorough explanation and dispels doubts regarding the suitability of the 5-hour PAV as an alternative for simulating the short-term aging of asphalt binders, thereby enhancing research facilitation. Furthermore, the research delineates the impact of various short-term aging simulation methods on the long-term aging properties of asphalt binders, including the variation rates between them.

Research on the Road Performance of Ring Diamond Resin Modified Asphalt Mixture

In order to solve the problems of ineffective modification and high cost of most asphalt modifiers, a new type of high viscosity and high elasticity asphalt modifier - ring diamond resin is introduced, and this modifier is injected into 70 # base asphalt. Through high-temperature rutting, low-temperature bending, immersion Marshall and freeze-thaw splitting tests, the road performance of 70 # base asphalt and ring diamond resin modified asphalt mixture is compared and analyzed. Intended to improve the quality of asphalt pavement while reducing economic costs, thereby extending the service life of the road. The research results indicate that the ring diamond resin modifier can greatly improve the high-temperature performance of asphalt mixtures, and to a certain extent improve their low-temperature crack resistance and water stability. It is a resin modified material with great potential and high advantages. It is recommended to use a dosage of 1% in practical road engineering applications.

Superior molten FLiBe salt barrier properties of a mesophase-pitch-based carbon/carbon composite prepared via hot isostatic pressing

Carbon/carbon (C/C) composites are promising structural materials for molten salt reactors (MSRs) because of their exceptional high-temperature performance, resistance to fluoride salt corrosion, and low-neutron-absorption cross-section. However, fluoride salts can infiltrate the pores of C/C composites, potentially causing local hotspots and accelerating material degradation. In this study, a novel C/C composite was fabricated from mesophase-pitch-based carbon fibers and a pitch-based carbon matrix via hot isostatic pressing (HIP). To evaluate its performance under MSR conditions, the composite was exposed to molten FLiBe salt at 700 °C and 2–9 atm for a duration of 20 h. Weight gain, morphological characteristics, and crystallinity were characterized after the salt infiltration test. Compared with C/C composites fabricated via conventional chemical vapor infiltration (CVI), the HIP-C/C composite exhibited much better molten salt barrier properties owing to its compact structure and small pore diameter. The weight gain of the HIP-C/C composite was only 0.17 wt.% under 5 atm, significantly lower than the critical index proposed for carbon materials used in MSR. Morphological characterization revealed that FLiBe salt particles were rarely trapped in the small pores of the HIP-C/C composite. While the crystallinity of the salt-impregnated CVI-C/C composite increased, the HIP-C/C composite exhibited a slightly decreased degree of graphitization after salt infiltration. These findings provide insights into the design of high-performance C/C composites for applications in MSR systems.

A comprehensive assessment of mechanical and environmental properties of waste basalt powder-modified high strength mortars exposed to high temperature

Waste Basalt Powder (BT) is a stone cutting workshop waste. The BT was recycled in the high strength mortars by Portland cement (PC). High temperature performance of the mortars were determined up to 800 ºC by in terms of weight and strength losses. The global warming potential (GWP) and Primary Energy (PE) of the mortars were calculated by Life Cycle Assessment (LCA) for the mortars and their environmental impacts were evaluated. GWP and PE decreased up to 23.9 % and 22.4 % in BT-containing mortars compared to the control group, respectively. Lower CO2 emission and PE values were determined in all the BT-containing mortars compared to the control group. Mortars containing 15 % BT had 9.92 % higher compressive strength than the control group with 14.35 % and 13.44 % lower GWP and PE values, respectively. The optimum BT content is 15 % in terms of strength, high temperature resistance and environmental impact. As a result, it is possible to successfully recycle BT material in the production of high-strength mortar that is more resistant to high temperatures.

High-Temperature Characteristics of Polyphosphoric Acid-Modified Asphalt and High-Temperature Performance Prediction Analysis of Its Mixtures

To promote the application of economical and sustainable polyphosphoric acid (PPA)-modified asphalt in road engineering, styrene-butadiene block copolymer (SBS), styrene-butadiene rubber (SBR), and PPA were used to prepare PPA/SBS and PPA/SBR composite-modified asphalts, which were tested and the data analyzed. Fourier transform infrared spectroscopy (FTIR) tests and thermogravimetric analysis (TG) tests were carried out to study the modification mechanisms of the composite-modified asphalts, and the high-temperature performance of the PPA-modified asphalt and asphalt mixtures was analyzed by dynamic shear rheology (DSR) tests and wheel tracking tests. A gray correlation analysis and a back-propagation (BP) neural network were utilized to construct a prediction model of the high-temperature performance of the asphalt and asphalt mixtures. The test results indicate that PPA chemically interacts with the base asphalt and physically integrates with SBS and SBR. The PPA-modified asphalt has a higher decomposition temperature than the base asphalt, indicating superior thermal stability. As the PPA dosage increases, the G*/sinδ value of the PPA-modified asphalt also increases. In particular, when 0.6% PPA is combined with 2% SBS/SBR, it surpasses the high-temperature performance achieved with 4% SBS/SBR, suggesting that PPA may be a good alternative for polymer modifiers. In addition, the creep recovery of PPA-modified asphalt is influenced by the stress level, and as the stress increases, the R-value decreases, resulting in reduced elastic deformation. Furthermore, the BP neural network model achieved a fit of 0.991 in predicting dynamic stability, with a mean percentage of relative error (MAPE) of 6.15% between measured and predicted values. This underscores the feasibility of using BP neural networks in predictive dynamic stability models.

Improved tribological behavior of Ti-6Al-4V through a novel zirconium diffusion coating

Titanium alloys, especially Ti-6Al-4V, are widely applied in the aerospace, automotive, marine, medical, and chemical industries due to their high strength, low density, good corrosion resistance, and high-temperature performance. However, the low wear resistance of Ti-6Al-4V hinders its broader applications. In this study, the influence of five different surface modifications on the tribological behavior of Ti-6Al-4V is compared. The five surface modifications were categorized as: 1) single-step process (oxidation), 2) two-step process (oxidation+reduction), 3) three-step process (oxidation+reduction+reoxidation), 4) oxidation at reduced oxygen partial pressure, and 5) a newly developed Zr slurry diffusion coating followed by subsequent oxidation to form ZrO2-enriched TiO2 on the surface. The wear tests were performed using a Si3N4 ball counterpart with a load of 5 N at a sliding velocity of 5.25 · 10−2 m/s and with a total sliding distance of 300 m. The wear mechanism for the unmodified Ti-6Al-4V was predicted and observed to be the detachment of Si3N4 particles from the counterpart and metallic particles from the substrate, subsequent oxidation of these particles via tribochemical reactions, and the adherence of the oxidized wear debris into the substrate and counterpart surface grooves. Deep ploughing grooves were not evident in the wear tracks of any surface-modified Ti-6Al-4V materials. Instead, wear debris containing Si-rich oxides formed as a tribolayer, except for the two-step processed sample. All surface treatments led to narrower and shallower wear tracks and there was no measurable material removal for the Zr diffusion-coated sample under the investigated conditions.

Effects of Aging on Rheological Properties and Microstructural Evolution of SBS Modified Asphalt and Crumb Rubber Modified Asphalt Binders

Focusing on the comparison of aging resistance between styrene-butadiene-styrene (SBS) modified asphalt (SBSMA) and crumb rubber modified asphalt binders (CRMA), the influences of aging on rheological properties and microstructural characteristics of different modified asphalts were investigated in this work. Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) tests were carried out, and the variations in rheological properties for different modified asphalts after the rotating thin film oven test (RTFOT) were analyzed with the rutting factor aging index (RAI) and creep rate aging index (CAI). By using Fluorescence microscopy (FM) and Fourier transform infrared (FTIR) spectroscopy, the evolutions of microstructure and chemical composition for two modified asphalts were analyzed with carbonyl index growth rate (CIR) and sulfoxide index growth rate (SIR). Then, The relationships between CIR/SIR and RAI/CAI were established to show the correlation between the deterioration of macroscopic performance and the evolution of micro-structure. The results indicated that the aging degree of asphalt increases with elevated temperatures, leading to decreasing low-temperature performance while improving high-temperature performance. Nevertheless, SBSMA exhibited strong sensitivity to aging temperature. Under thermo-oxidative aging, the RAI and CAI of SBSMA were lower than those of CRMA, whereas the regularities of CIR and SIR were opposite, indicating that CRMA was superior to SBSMA in terms of anti-aging properties due to the rupture of the cross-linked network structure of SBSMA. However, CRMA experienced aging accompanied by full swelling, and thus, relatively minor performance declined. The CIR and SIR exhibited a better correlation with the RAI and CAI, illustrating that both CIR and SIR could characterize the aging degree of modified asphalts well.

Soft solution state and hard aging state of Inconel 718 reached via optimized precipitation elements using cluster formula approach

The superior high-temperature performance of Inconel 718 is originated mainly from the precipitation strengthening via Nb, Al, and Ti alloying. Inappropriate contents of the precipitation elements may lead to over-strengthened solution state and insufficiently strengthened aging state. We have previously identified the alloy composition formula [(Nb,Al,Ti)1-(Ni,Fe,Cr,Mo)12](Ni,Fe,Cr,Mo)5 using the cluster formula approach, where the 18-atom structural unit is composed of a nearest-neighbor cluster, centered by one precipitation elements, plus five glue atoms situated at the next neighbors. On the basis of this formula, the present work designs a series of alloys using (Nb,Al,Ti) = 0.93, 1, and 1.06, with 4.9 and 5.5 wt % Nb, 0.68 and 0.5 wt % Al, and 1.10 wt% Ti corresponding to the upper-to-middle ranges in the ASTM standard. In particular, when the total number of atoms in the formula is equal to one, (Nb0.6Al0.2Ti0.2), the alloy is soft at the solution state (σUTS = 825 MPa < 965 MPa of the standard and EL = 70.3 % > 30 %) and reaches high strength levels after aging (σUTS = 1400 MPa > 1240 MPa and EL = 23.4 % > 12 % at room temperature, σUTS = 1100 MPa > 965 MPa and EL = 10.2 % > 5 % at 923 K). This alloy also shows the lowest coarsening rate of 4–7 × 10−3 nm3 s−1 after long-term aging at 923 K, lower than the prevailing coarsening rate of about 16 × 10−3 nm3 s−1.