Phase Decomposition Research Articles

Redox Stability and Electrical Properties of the High‐Entropy (Pb0.2Ca0.2Ba0.2Sr0.2Mg0.2)0.7La0.3WO4.15 Oxide Ion Conductor

Donor‐doped Pb1−xLaxWO4 (x ≤ 0.3) materials are well‐known for their high oxygen ionic conductivity. However, their poor phase and redox stabilities under a reducing atmosphere hinder their practical applications, such as electrolytes for solid oxide fuel cells. In this work, a high‐entropy (Pb0.2Ca0.2Ba0.2Sr0.2Mg0.2)0.7La0.3WO4.15 material is prepared through a traditional solid‐state reaction method, aimed to enhance the phase and redox stability of the material under reducing atmosphere. The results reveal that this material has high phase and structural stability in high oxygen partial pressure environments. However, it will still undergo phase decomposition, yielding impurity, and introducing strong electronic conduction, showing even lower redox stability and phase stability than the non‐high‐entropy counterpart Pb0.7La0.3WO4.15. Thus, improving the phase and redox stabilities under reducing atmospheres of the PbWO4‐based materials is still the main challenge in the future.

The evolution, characteristics, and driving forces of the rural-urban HCEs in China: based on the EIO-SDA model

Households' carbon emissions (HCEs) plays an important role in the overall carbon emission (CE) reduction. This study conducts a comparative analysis of the trends and characteristics of the rural and urban HCEs in China in 1997–2020, by applying the environmental input-output (EIO) model. Then, a three-stage SDA model is applied to decompose the driving forces of the rural and urban HCEs evolution into population effect, per capita HCEs effect, expenditure effect, CE intensity effect, energy structure effect, and energy consumption intensity effect. It is obtained that the rural HCEs increases before 2015 and then decreases, but its per capita HCEs has always shown an upward trend. The urban HCEs has been increasing, but its per capita HCEs starts to decrease after 2015. Indirect HCEs accounts for over 80% of both the rural and urban HCEs, and Residence, Food and Tobacco, Transportation and Communication are the three biggest contributing sectors. To reveal the driving forces of the rural and urban HCEs evolution, this study conducts phase decomposition analysis with 2015 as a turning point. For rural HCEs, in 1997–2015, rural HCEs increased due to the dominant expenditure effect; from 2015 to 2020, the driving force reversed, leading to a decline in rural HCEs. For urban HCEs, the positive population and expenditure effects have always been larger than the negative energy structure and energy consumption intensity effects, resulting growth in urban HCEs. For urban per capita HCEs, in 1997–2015, the positive expenditure effect is greater than the negative CE intensity effect, leading to an increase in urban per capita HCEs, and a positive urban per capita HCEs effect. In 2015–2020, the driving force reversed, leading to a decline in urban per capita HCEs. Based on above results, countermeasures to promote rural and urban HCEs reduction are discussed.

Changes in the structural properties of polycrystalline oxide La<sub>2</sub>O<sub>3</sub> at heating it in air and in vacuum

Changes in the phase’s structure of polycrystalline La2O3 upon heating in air and vacuum have been established. For the first time, on La2O3 samples after annealing in the range 700‒1900 оC in air, the microstructure of a monoclinic phase of type B and a hexagonal phase of type A with the presence of texture was obtained. For the first time, after annealing La2O3 samples at 1900 °C in air, the formation of loops and screw dislocations on La2O3‒х grains was discovered, through which the evaporation of crystals of different colors and the decomposition of hexagonal phase grains into cubic phase crystals of type F with an fcc lattice and type C with a bcc lattice occurred. For the first time, it has been theoretically substantiated and experimentally confirmed that heating lanthanum oxide samples at 1750 and 1900 °C leads to the decomposition of the hexagonal phase of type A with the presence of texture into two cubic phases: type F with the content of anionic vacancies and a crystal lattice parameter a = 0.5677 nm (Fm3m) and type C containing color centers and a = 1.14838 nm (Ia3). The refractive indices of these phases were determined. The energy of formation of anion vacancies in the lattice of the hexagonal phase of type A is calculated and the critical concentration of anion vacancies leading to the decomposition of this phase is determined.

Insight into the oxidation behavior and excellent internal oxidation and nitridation resistance of Fe71.5-x(Ni, Cr, Ti)28.5Alx complex concentrated alloys by advanced characterization

For precipitate-strengthened alloys, the decomposition of the precipitates at the subsurface during high-temperature oxidation is detrimental to mechanical properties. In this study, we adjusted Al concentrations in Fe71.5-x(Ni, Cr, Ti)28.5Alx (x = 8, 12, and 16 at. %) complex concentrated alloys (CCAs) to precipitate elongated cuboidal L21 with higher density and Al concentration, as well as reduced inter-precipitate spacing. This is more conducive to the rapid diffusion of Al to the matrix and grain boundaries, promoting the formation of a continuous and compact Al2O3 layer with random crystallographic orientation at 800 °C in air. This not only inhibits the further decomposition of the L21 phase but also avoids internal oxidation and nitridation.

High-temperature shrinkage compensation of cesium-based geopolymer: Synergistic effects of kyanite decomposition, ceramization and phase transformation

Cesium-based geopolymers and their ceramization product, pollucite, exhibit excellent heat resistance and considerable potential as engineering materials for high-temperature environments. However, the substantial shrinkage of cesium-based geopolymer during the ceramization process hinders its wide application. In this study, cesium-based geopolymer composites were prepared and evaluated on their shrinkage compensation, with the addition of reinforcing phases of kyanite or corundum. Compared with the sample with the addition of corundum, the linear shrinkage of the sample with the addition of kyanite after heat treatment at 1400 °C was reduced from 15.30 % to 6.28 %, showing a decrease by 54.89 % in linear shrinkage. There was no reaction between kyanite and geopolymer at room temperature, and the ceramization process of the cesium-based geopolymer was not altered either. The decomposition of kyanite at 1200–1400 °C during heat treatment produced mullite and silica, which expanded the volume by 18 %. This compensated for the shrinkage that occurred during the subsequent processes of ceramization and sintering of geopolymer. Mullite and silica further reacted with CsAlSiO4-ANA (having the same cubic ANA type zeolite framework as pollucite) to form corundum and pollucite (CsAlSi2O6) at 1300–1400 °C, during which the average size of pollucite grains increased from 1.82 μm to 4.34 μm, with an increase of 238.46 %. The reaction in this stage prevented the volatilization of cesium in the high temperature, and the increase of pollucite particle size reduced the shrinkage and porosity. This study cast the light on the design and preparation of low-shrinkage, ceramizable, geopolymer composites by synergistic effects of kyanite decomposition, ceramization and high-temperature phase transformation.

Effect of kinematics on ground reaction force during single-leg jump landing in children: a causal decomposition approach in jumpers and non-jumpers.

The interaction between joint kinematics and kinetics is usually assessed by linear correlation analysis, which does not imply causality. Understanding the causal links between these variables may help develop landing interventions to improve technique and create joint-specific strengthening programs to reduce reaction forces and injury risk. Therefore, the aim of this study was to analyze the causal interaction between lower limb sagittal kinematics and vertical ground reaction force (VGRF) during single-leg jump landing in children who are jumpers (volleyball and gymnastics) and non-jumpers, using the causal empirical decomposition method. Our hypothesis is that children who participate in jumping sports, compared to those who do not, employ a different joint strategy to regulate ground reaction forces during landing, particularly at the ankle level. Two groups were compared: the jumpers group (n = 14) and the non-jumpers (control group, n = 11). The causal interaction between sagittal kinematics and VGRF was assessed using ensemble empirical mode decomposition (EEMD) and time series instantaneous phase dependence in bi-directional causality. The relative causal strength (RCS) between the time series was quantified as the relative ratio of absolute cause strength between kinematics and VGRF. A significant interaction between joint and group was found for RCS (p = 0.035, η 2 p = 0.14). The post-hoc analysis showed the jumpers group had higher ankle-to-VGRF RCS than the control group (p = 0.017, d = 1.03), while in the control group the hip-to-VGRF RCS was higher than the ankle-to-VGRF RCS (p = 0.004, d = 0.91). Based on the causal decomposition approach, our results indicate that practicing jumping sports increases the causal effect of ankle kinematics on ground reaction forces in children. While non-jumper children rely more on the hip to modulate reaction forces, jumper children differ from non-jumpers by their greater use of the ankle joint. These findings could be used to develop specific training programs to improve landing techniques according to practice level, potentially helping to reduce the risk of injury in both athletes and non-athletes.

The Molecular Additive N-Acetyl-L-Phenylalanine Delays the Crystallization and Suppresses the Phase Impurity for Achieving Triple-Cation Perovskite Solar Cells with Efficiency Over 25.

The crystallization process plays an important role in the formation of high-quality perovskite film for achieving efficient perovskite solar cells (PSCs), especially in the formation of mixed-cation perovskite film, as there are normally more phase impurities than in pure CH(NH2)2PbI3 (FAPbI3) film. Herein, a molecular additive strategy, i.e., introducing non-planar molecule N-acetyl-L-phenylalanine (APO) into the lead iodide (PbI2) precursor solution, is proposed to modulate crystallization kinetics and inhibit the generation of phase impurities of metastable pretreated perovskite film. The delayed crystallization process promotes a sufficient reaction between organic salts solution and inorganic Pb-I framework, and perovskite phase decomposition is prevented by forming strong hydrogen bonds between ─NH and I, resulting in the formation of uniform film with large-size crystal grains and high-purity crystalline phase. Ultimately, the target PSC devices achieve an impressive power conversion efficiency (PCE) of 25.05%, which is among the highest values of triple-cation (FAMACs) PSCs. Meanwhile, PSC modules with 10.8 cm2 obtain a PCE of 20.35%. Furthermore, the unencapsulated PSCs retain 94% of the initial efficiency after 40 days of storage under ambient conditions with 20% RH and also yield superior operational stability under light soaking at maximum power point tracking (MPPT) in nitrogen (N2) atmosphere.

Mathematical modeling of ozone decomposition processes in wastewater treatment: A lumped kinetic approach with initial ozone demand

Ozone-based processes involve complex reaction networks and exhibit matrix-dependent decomposition patterns when dosed to wastewater effluents. Existing models for ozone decomposition are either too complex or not sufficiently descriptive of the regime manifested during initial ozone demand and decay. Models incorporating detailed reactions have shown limited applicability due to the high number of initial states and state variables involved. This study introduces a new mathematical model that balances accuracy and complexity in describing the main phases of ozone decomposition in secondary wastewater effluents. Specifically, a simplified model is proposed based on lumped variables, including initial ozone demand, two classes of organic matter (slow and fast reacting), radical forming (and ozone-decomposing) compounds, radical scavengers, and a hypothetical target contaminant. Results revealed that the model can predict with reasonable accuracy both the rapid initial ozone demand (occurring at very short timescales <10 s) and the slower ozone decomposition processes (occurring at longer timescales >30 s). A global sensitivity analysis was also conducted to further model refinement and simplification, which led to the elimination of three reactions connected to the generation and consumption of radicals (threshold |RXY| ≥ 0.05). Satisfactorily low residual values (RMSE≤7·10−6 M) were observed in all cases. Finally, the adequacy of the model was further tested against an independent set of ozone decomposition experiments obtained from the literature, confirming its suitability in describing ozone decomposition in secondary wastewater effluents with initial ozone demand.

Effect of Deformed Prior Austenite Characteristics on Reverse Phase Transformation and Deformation Behavior of High-Strength Medium-Mn Steel.

In this study, microstructure evolution during prior austenite decomposition and reverse phase transformation processes was revealed in a high-strength medium-Mn steel. Furthermore, the relationship between deformed prior austenite characteristics and deformation behavior was studied. The results indicated that the recovery and recrystallization of the deformed prior austenite were significantly inhibited during hot rolling in the non-recrystallized zone, the grain size was obviously refined along the normal direction (ND), and that the strain hardening of prior austenite via hot deformation could increase the resistance of shear transformation, resulting in the preservation of high-density lattice defects in the quenched martensite matrix. Before the nucleation of intercritical austenite, the dislocation and grain boundary can provide fast diffusion paths for C and Mn, and the enrichment of C and Mn before intercritical austenite formation can reduce the critical temperature of ferrite/austenite transformation. The nucleated sites and driving force for intercritical austenite were strongly increased by rolling in the non-recrystallization region. The resistance of crack propagation was found to be enhanced by the sustained transformation-induced plasticity (TRIP) effect (via retained austenite with different stability) and for the laminated microstructure, the optimum properties were obtained as being a combination of yield strength of 748 MPa, tensile strength of 952 MPa, and total elongation of 26.2%.

Influence of Nitrogen Content on the Microstructure Evolution and Oxidation Resistance toward Ambient Air of CrAlSiN Coatings Deposited by FCVAD Technique.

In this study, CrAlSiN coatings with nitrogen contents ranging from approximately 42 to 54 at. % were deposited and subsequently exposed to temperatures of 700 or 900 °C for 2 h in ambient air to investigate the impact of nitrogen content on the microstructure evolution and high-temperature oxidation resistance. It was found that the CrAlSiN coating with nitrogen content of 42-45 at. % exhibited an amorphous/nanocrystalline hybrid structure, comprising pure metallic Cr and (Al,Cr)N phases within the matrix, as determined by the TEM, XRD, and XPS analysis. In contrast, as the nitrogen content exceeded 52 at. %, the coatings transformed to a dominantly columnar structure featuring solely Cr(Al)N phase. The CrAlSiN coating with a nitrogen content of ∼52 at. % retained amorphous fraction of around 20% but demonstrated superior oxidation resistance with the lowest parabolic rate constant of 1.1 × 10-14 cm2/s at 900 °C compared to other coatings. This enhanced performance was primarily attributed to the high stability of Cr(Al)N phase and formation of a fine-columnar/amorphous microstructure devoid of metallic Cr, resulting in a significantly thin (∼60 nm) yet dense Al2O3-rich monolayer atop the coating surface during the oxidation. Conversely, substoichiometric CrAlSiN coatings with N content ≤45 at. % would form a thick Cr2O3 outer layer over an underlying Al2O3 layer. Additionally, elemental segregation of Cr, Si, and Al was observed in all CrAlSiN coatings after exposure to 900 °C for 2 h, which was induced by the spinodal decomposition of the ternary nitride phases.

In-situ construction of heterogeneous structure by crystal phase evolution to improve the sodium storage performance of NiCo2O4

Transition metal oxides (TMCs) have great potential in sodium ion batteries (SIBs) due to their significantly higher capacity and lower cost. However, during the cycle, huge volume changes often lead to structural damage, which is a key factor in the rapid decay of capacity. In this paper, a heterogeneous structure was constructed in situ by introducing sulfur element to induce the decomposition of NiCo2O4 crystal phase. The rich heterogeneous interface has enhanced redox reaction kinetics and charge transport properties. For high-capacity conversion anode materials, cross-linked grain boundaries can effectively disperse the local stress caused by volume changes and alleviate the inevitable electrode crushing, thus ensuring the stability of the electrode during long-term cycling. The NiCo2O4/NiCo2S4/CoO/ NiO heterogeneous structure (NCOS-350) exhibits enhanced cycling and rate performance (350 mAh g−1 at 0.5 A g −1 after 100 cycles and 270 mAh g −1 at 5 A g −1) when used as the anode for sodium ion batteries. In addition, it is proved that NCOS-350 has smaller volume change and better structural stability than NiCo2O4 by scanning electron microscopy and other characterizations.

Bench-scale thermomechanical assessment of carbon fibre reinforced polymer C-channels

This study investigates the thermomechanical response of carbon fibre reinforced polymer (CFRP) C-channels using a bench-scale apparatus that combines mechanical loading and radiant thermal exposure. The study aims to assess the behaviour of pre-loaded CFRP C-channels, representative of aircraft sub-structures when subjected to fire conditions. Woven prepreg CFRP C-channels were tested under cantilever point load deflection while exposed to varying heat fluxes. Key aspects examined during the study include failure times, displacement, temperature distribution, and failure modes. The findings reveal that heated, pre-loaded C-channels experience distinct phases of physico-chemical decomposition and mechanical degradation. The mechanical degradation includes upward shear buckling of the horizontal flanges and vertical web, along with outward buckling of the vertical web towards the heat source. The study shows that thermal decomposition and mechanical degradation occur simultaneously, influenced by heat flux intensity. Higher heat fluxes accelerate decomposition and reduce load-bearing capacity, while lower fluxes slow degradation. Displacement data indicates that heat flux intensity significantly affects structural response. Temperature measurements show higher fluxes lead to elevated temperatures and steeper gradients, impacting failure times and modes. Increased temperatures correlate with shorter failure times, and variability in failure times decreases as heat flux rises. These insights are significant for understanding the thermomechanical response of C-channels in aircraft sub-structures. The knowledge obtained can contribute to developing more robust and safer aircraft designs, particularly for components exposed to fire conditions, enabling engineers to establish more precise safety margins for CFRP structures, potentially preventing catastrophic failures and thereby enhancing overall aircraft safety.

Formation ability, phase decomposition and mechanical properties of Ti39Zr39Ni20Ag2 and Ti39Zr39Ni20Cu2 bulk icosahedral quasicrystalline alloys

An icosahedral quasicrystalline (IQ) phase forms in the as-spun ribbons as well as as-cast bulk rods with a diameter of 2 mm for the Ti39Zr39Ni20Ag2 and Ti39Zr39Ni20Cu2 alloys. The Ti39Zr39Ni20Ag2 alloy ribbon consists of a mostly amorphous phase containing a small amount of IQ phases and exhibits good bending plasticity. The decomposition of their metastable phases occurs accompanying exothermic peaks at 694 K and 890 K, followed by an endothermic peak at 991 K. The former two peaks are due to the transitions from amorphous to IQ + cF96-(Ti, Zr)2Ni phases, and to C14-TiZrNi Laves phase, respectively. The latter endothermic peak originates from the change of IQ to C14-TiZrNi Laves and β-(Ti, Zr) phases. Compared with the complex phase decomposition behavior of the quaternary alloys, the decomposition of the metastable phase of the Ti40Zr40Ni20 alloy ribbon occurs accompanying only an endothermic peak at a peak temperature of 952 K, followed by a melting peak. For the quaternary alloys, the as-cast rods consist of an IQ single phase, in contrast to three phases of IQ, C14-TiZrNi Laves and β-(Ti, Zr) phases for the Ti40Zr40Ni20 rod. The ternary alloy rod fractures in the quasi-cleavage fracture mode, while the fracture mode of the quaternary alloy rod is cleavage fracture. In the Ti39Zr39Ni20Ag2 rod, IQ phase displays a spherical morphology with an average diameter of approximately 0.27 μm. The formation of the bulk IQ rod as well as the enhancement of amorphous phase formability for the Ag/Cu-containing IQ alloys are presumably due to the stabilization of supercooled liquid caused by the development of more dense-packed atomic configurations resulting from the sequent atomic size change of Zr > Ti > Ag/Cu > Ni as well as by the necessity of the separation to Ti-Zr-Ni and Ti-Zr-Ag/Cu atomic pairs resulting from the positive heats of mixing for Ni-Ag and Ni-Cu pairs.

Critical current degradation of commercial REBCO coated conductors under thermomechanical loads

Abstract The process to obtain a superconducting joint between Coated Conductors (CCs) involves the simultaneous application of temperature and transverse compressive pressure to promote the joining of the two adjacent REBCO layers. We performed experiments to simulate this procedure by subjecting samples from commercial CCs to different combinations of pressure, and temperature. The objective was to understand the effects of the thermomechanical cycles on the critical current (Ic) and, therefore, determine the upper limit for the achievable current in a superconducting joint between CCs. We observed a reduction of the Ic across the investigated parameter range that is accelerated at higher temperatures and pressures. For instance, the average reduction of Ic measured at 77 K in self-field varied from 45% to 90% when increasing the pressure for samples heated at 820 °C, as compared to samples heated at the same temperature without applied pressure. As a complement to electrical transport measurements, we carried out TEM and EDX investigations to study the relation between the degradation of Ic and alterations in the microstructure of REBCO. These analyses indicate that the concurrent application of temperature and pressure accelerates the decomposition of the REBCO phase. The EDX data suggests that the decomposition products could correspond with a peritectic reaction of the REBCO occurring at lower temperatures, accelerated by the presence of an external pressure. This early decomposition occurs in localized areas of the REBCO layer, constricting the available cross-section for current flow and thereby diminishing the critical current.

High-entropy doping for high-voltage LiCoO2 with enhanced electrochemical performances

Lithium cobalt oxide (LiCoO2), as a pioneering layered oxide cathode material for lithium-ion batteries (LIBs), possesses exceptional theoretical specific capacity and cycling stability, positioning it as a leading candidate for commercial LIB applications. Boosting the upper-limit of charge voltage of LiCoO2 is a promising strategy to increase the capacity of batteries, vital for advancing energy storage solutions from portable electronics to electric vehicles. Nevertheless, hybrid redox reactions at high voltages speed up oxygen evolution, electrolyte decomposition, and irreversible phase transitions, ultimately causing rapid capacity fading.To address these challenges, we present a novel approach to enhance the structural stability and electrochemical performances of LiCoO2 cathode via La-Al-Mg-Y high-entropy doping. This strategy significantly improves the high-voltage cycling stability of the cathode material by retaining 72.5 % of its initial capacity after 500 cycles at 5 C under 4.6 V. Furthermore, the structural change caused by the phase transition between the O3 and H1-3 phases is remarkably suppressed. This advancement in LIB cathode technology paves the way for the development of high performance batteries and it is crucial for meeting the growing demand for sustainable energy storage.

The influence of CuxS particles on the thermal decomposition of anion exchangers

Due to the versality, surface imperfections and diverse redox chemistry of CuxS, hybrid ion exchangers (HIXs) containing these particles are an interesting object of research, including thermal transformation. The composite materials used for testing were strongly basic anion exchangers, with macroreticular (M) and gel-type structure (G), containing in the poly (styrene/divinylbenzene) skeleton fine particles of covellite/brochantite (M1), covellite (M2), covellite/digenite/djurleite (G1) and covellite/digenite (G2). The prepared HIXs contained 12–16 mass% S + Cu. They were subjected to thermal analysis under air and N2 to identify the role of the inorganic phase in decomposition of the polymeric phase. The results were discussed on the basis of the TG/DTG curves and X-ray diffraction (XRD) patterns of the solid residues (CuO after combustion, carbon/Cu2S after pyrolysis). It was found that CuxS in the resin phase exhibited oxidative activity promoting the combustion process. The polymeric skeleton of HIXs decomposed in air at a much lower temperature compared to pure resins (400 vs 600 °C). The TG/DTG curves had a model shape, three separate conversions occurring in a narrow temperature range, which indicated sequential decomposition. The low consumption of hydrogen for the reduction of CuxS to Cu2S during pyrolysis was not conducive to condensation of alkyl radicals and increase of the mass of carbon matter. The results advance the understanding of the effect of copper/sulfur-containing fine particles on the thermal decomposition of anion exchanger and can be useful in preparation of multifunctional carbon-containing composite materials.

Mineralogical and thermal analysis of the Neolithic ceramic from Ghaf Khāneh, a late Sixth millennium BCE site in Northeast Iran

Mineralogical and thermal analysis have examined Neolithic ceramic sherds from Ghaf Khāneh, a site dated ca. 5200–5000 BCE, i.e., the early phase of Cheshmeh Ali culture in northeast Iran. This research includes fifteen sherd fragments recovered from archaeological excavation at this site. The ceramic assemblage of the site is overwhelmed by the Red Ware, comprising almost 95 percent of the whole, while the Gray Ware and Buff Ware constitute minor ceramic groups. This study aims to identify each ceramic group’s mineralogical and chemical characteristics and evaluate the mineralogical behavior (phase decomposition) during the firing process, kiln atmosphere, the firing temperature, and factors that may affect the mineral behavior. Buff and Red Ware display diopside and hematite phases within their fabrics, which indicate the role of these phases in coloring. The studied samples contained muscovite, calcite, and microcline phases; these phases have been considered thermobarometers. According to petrographical studies, XRD analysis, and TG-DTA curves, Red Ware and Buff Ware can be classified into two groups: those fired above 850 °C and those fired below 750 °C, while Gray Ware was fired below 750 °C. Certain phases in the studied samples may provide insight into ancient potters’ knowledge and familiarity with various clayey resources.

Formation and strengthening mechanism of high entropy nugget for aluminum/steel resistance rivet welding

Resistance rivet welding (RRW) was a promising joining process for aluminum (Al) alloy and steel. The high entropy mixed nugget (HEMN) with the composition of Al0.8CoCrFe1.6Ni was obtained by introducing a high entropy alloy (HEA) rivet in RRW process. The high entropy played a significant role in facilitating the formation of solid solution. The HEMN microstructure exhibited a nanometer-sized weave-like structure caused by spinodal decomposition, comprising both BCC and B2 phases. The average hardness of the HEMN exceeded that of the Al/Steel mixed nugget, resulting in higher lap-shear strength and ductility. The analysis of strengthening mechanism demonstrated that the lattice misfit and order strengthening were the primary contributors. This study provided a novel strategy for joining dissimilar metal materials.

Evaluating the Impact of Interferogram Networks on the Performance of Phase Linking Methods

In recent years, phase linking (PL) methods in radar time-series interferometry (TSI) have proven to be powerful tools in geodesy and remote sensing, enabling the precise monitoring of surface displacement and deformation. While these methods are typically designed to operate on a complete network of interferograms, generating such networks is often challenging in practice. For instance, in non-urban or vegetated regions, decorrelation effects lead to significant noise in long-term interferograms, which can degrade the time-series results if included. Additionally, practical issues such as gaps in satellite data, poor acquisitions, or systematic errors during interferogram generation can result in incomplete networks. Furthermore, pre-existing interferogram networks, such as those provided by systems like COMET-LiCSAR, often prioritize short temporal baselines due to the vast volume of data generated by satellites like Sentinel-1. As a result, complete interferogram networks may not always be available. Given these challenges, it is critical to understand the applicability of PL methods on these incomplete networks. This study evaluated the performance of two PL methods, eigenvalue decomposition (EVD) and eigendecomposition-based maximum-likelihood estimator of interferometric phase (EMI), under various network configurations including short temporal baselines, randomly sparsified networks, and networks where low-coherence interferograms have been removed. Using two sets of simulated data, the impact of different network structures on the accuracy and quality of the results was assessed. These patterns were then applied to real data for further comparison and analysis. The findings demonstrate that while both methods can be effectively used on short temporal baselines, their performance is highly sensitive to network sparsity and the noise introduced by low-coherence interferograms, requiring careful parameter tuning to achieve optimal results across different study areas.

Boron nitride nanosheets composite SiC fibers with enhanced mechanical properties and high‐temperature resistance

AbstractContinuous SiC fibers with excellent mechanical properties and high‐temperature resistance possess immense potential as reinforcements for aeroengines. In this work, we prepared functionalized boron nitride nanosheet (F‐BNNS) composite SiC (F‐BNNS/SiC) fibers by polymer‐derived method. Due to the existence of F‐BNNS, the F‐BNNS/SiC fibers demonstrate an improved tensile strength up to 2300 MPa, representing a 25% increase compared to the original SiC fibers. Furthermore, owing to the chemical bonds established between the F‐BNNS and the SiCxOy network, the decomposition of the SiCxOy amorphous phase and the crystallization of SiC at high temperatures is effectively suppressed. The F‐BNNS/SiC fibers exhibit improved high‐temperature resistance, maintaining a tensile strength of 720 MPa up to 1500°C, while the SiC fibers completely degraded under the same conditions. The successful preparation of BNNS/SiC fibers may offer new insights into the performance enhancement of advanced ceramic fibers.