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Abstract: As a promising candidate for nonvolatile memory devices, the hafnia‐based ferroelectric system has recently been a hot research topic. Although significant progress has been made over the past decade, the endurance problem is still an obstacle to its final application. In perovskite‐based ferroelectrics, such as the well‐studied Pb[ZrxTi1−x]O3 (PZT) family, polarization fatigue has been discussed within the framework of the interaction of charged defects (such as oxygen vacancies) with the moving domains during the switching process, particularly at the electrode‐ferroelectric interface. Armed with this background, a hypothesis is set out to test that a similar mechanism can be in play with the hafnia‐based ferroelectrics. The conducting perovskite La‐Sr‐Mn‐O is used as the contact electrode to create La0.67Sr0.33MnO3 / Hf0.5Zr0.5O2 (HZO)/ La0.67Sr0.33MnO3 capacitor structures deposited on SrTiO3‐Si substrates. Nanoscale X‐ray diffraction is performed on single capacitors, and a structural phase transition from polar o‐phase toward non‐polar m‐phase is demonstrated during the bipolar switching process. The energy landscape of multiphase HZO has been calculated at varying oxygen vacancy concentrations. Based on both theoretical and experimental results, it is found that a polar to non‐polar phase transformation caused by oxygen vacancy redistribution during electric cycling is a likely explanation for fatigue in HZO.

Variations in the microstructure and the dominant fretting wear mechanisms of carbon steel alloy in oscillatory sliding contact against stainless steel in a dry atmosphere were evaluated by various mechanical testing and microanalytical methods. These included scanning electron microscopy and energy dispersive spectrometry with corresponding elemental maps of the wear tracks, in conjunction with cross-sectional transmission electron microscopy of samples prepared by focused ion beam machining to assess subsurface and through-thickness changes in microstructure, all as a function of applied load and sliding time. Heavily dislocated layered microstructures were observed below the wear tracks to vary with both the load and sliding time. During the accumulation of fretting cycles, the subsurface microstructure evolved into stable dislocation cells with cell walls aligned parallel to the surface and the sliding direction. The thickness of the damaged subsurface region increased with the load, consistent with the depth distribution of the maximum shear stress. The primary surface oxide evolved as Fe2O3 and Fe3O4 with increasing sliding time, leading to the formation of a uniform oxide scale at the sliding surface. It is possible that the development of the dislocation cell structure in the subsurface also enhanced oxidation by pipe diffusion along dislocation cores. The results of this study reveal complex phase changes affecting the wear resistance of steels undergoing fretting wear, which involve a synergy between oxidative wear, crack initiation, and crack growth along dislocation cell walls due to the high strains accumulating under high loads and/or prolonged surface sliding.

Many ceramic materials transform to a solid-solution intermediate state before amorphization under extreme conditions. Combining in-situ irradiation experiments and ab initio molecular dynamics simulations, we performed a comparative study of the defect accumulation process in MAX phases, Ti 2 AlC, Cr 2 AlC, and Ti 2 SnC, to clarify the correlation between solid-solution intermediate phase properties and phase instability. It is found that phase stability strongly depends on the lattice distortion of the solid-solution intermediate state, rather than the defect energies in the initial phases that were previously believed as the indicator of the resistance to the irradiation-induced amorphization. Larger lattice distortions of the solid-solution intermediate state can hinder defect recombination and lead to faster collapse to an amorphous state. This work provides a new research insight into phase instability for ceramic materials under extreme conditions. [ABSTRACT FROM AUTHOR]

We investigated the electrocatalytic properties of Ir/β‐MnO2, with 4.2–5.6 atomic % (at %) iridium. The Ir/β‐MnO2 was synthesized by heating Ir/R‐MnO2—formed via a surfactant‐assisted (SA) method using KMnO4, IrCl3.H2O, and sodium dodecyl sulfate (SDS)—to 400 °C. The Ir/β‐MnO2 (SA) was nano‐sized based on scanning and transmission electron microscopy (SEM and TEM). Using linear sweep voltammetry (LSV), 5.6 at % Ir/β‐MnO2 (SA) exhibited an overpotential (η) ${\eta){\rm \ }}$ of 327±5 mV for the oxygen evolution reaction (OER), at 10 mAcm-2 ${\hskip0.17em{{\rm c}{\rm m}}^{-2}}$ in 0.5 M H2SO4 electrolyte. At 10 mA cm-2 ${{{\rm c}{\rm m}}^{-2}}$ the Ir/β‐MnO2 (SA) catalyzed the OER for 72 h at an η ${\eta }$ of 534 mV. During this time there was a 12 % loss in Mn and 8 % loss in Ir from the structure. An IrO2 catalyst exhibited an initial η of 420±7 for the OER, but after 20 h of operation at 10 mA cm-2 ${{{\rm c}{\rm m}}^{-2}}$ there was a steep rise in potential (>550 mV) and 12 % loss in Ir. The enhanced activity and stability of Ir/β‐MnO2 (SA) is attributed to the incorporation of Ir into the MnO2 lattice during synthesis and the formation of nano‐sized particles using the SA method. [ABSTRACT FROM AUTHOR]

Multi‐mode luminescence tuning through in situ crystallization of topological glass holds significance for photonics applications. Here, NaAlSiO4:Eu2+‐based glass ceramics are presented as stable persistent luminescence (PersL) materials by controlling the phase transformation in Eu2+ doped Na2O‐Al2O3‐SiO2 from amorphous glass to crystalline nepheline phase. X‐ray and UV excited PersL colors from blue to yellow are realized by adjusting the crystallization duration time, and trap statuses reveal the dynamic PersL process with a trap redeployment from 0.83 to 1.09 eV during the transformation. Optical information storage model is constructed with a structure of stacked emitting layers to enhance storage capacity. X‐ray excited luminescence time‐lapse imaging is further demonstrated with optical memory longer than 5 days. These findings advance the development of superior stable PersL glass ceramics and offer optical manipulation tactics for multi‐mode optical information storage applications. [ABSTRACT FROM AUTHOR]

Production of Portland cement consumes a huge amount of silica mineral. The present work aims to introduce desert sand to replace the natural mineral to achieve green manufacturing of silicate cement clinker, as well as further decreasing the synthesis temperature and increasing the production efficiency. The effects of desert sand, industrial quartz and high‐purity quartz as raw materials, and Al2O3 and Fe2O3 as additives on phase transformation and microstructure of calcium silicate powder were comparably investigated using X‐ray diffractometer, differential scanning calorimeter, and scanning electron microscopy. Results show that the main phases of all samples with different raw materials and additives were 3CaO·SiO2 (C3S) and 2CaO·SiO2 (C2S). In which, the samples prepared using desert sand had the lowest phase transformation temperature for C2S and C3S. When adding Al2O3 and Fe2O3, the phase transformation temperatures of C2S and C3S further decreased, which were 1032.5°C and 1270.9°C, respectively, meanwhile phase content reached the maximum (C2S of 65.6 wt.% and C3S of 61.2 wt.%). In addition, the most uniformly and finely distributed crystalline phases formed at an optimal calcination temperature of 1350°C. This is beneficial for reducing production costs, saving mineral resources, and promoting the sustainable development of the cement industry. [ABSTRACT FROM AUTHOR]

Lithium/sodium–selenium (Li/Na–Se) batteries with high volumetric specific capacity are considered promising as next‐generation battery technologies. However, their practical application is hindered by challenges such as low Se loading in cathodes and the polyselenides shuttle effect. To address these challenges, a new Se host is introduced in the form of a free‐standing N, O co‐doped vertically aligned porous carbon framework decorated with a carbon nanotube forest (VCF‐CNTs), allowing for high mass loading of up to 16 mg cm−2. The low‐tortuosity Se@VCF‐CNTs architecture facilitates rapid lithiation/sodiation kinetics, while the CNT forests in vertical microchannels enhance efficient Se loading and serve as a multi‐layer fence to prevent undesired polyselenide shuttling. Consequently, the Se@VCF‐CNTs cathode displays a significant areal capacity of 10.3 mAh cm−2 at 0.1 C with a Se loading of 16 mg cm−2 for Li–Se batteries, exceeding that of commercial lithium ion batteries (4.0 mAh cm−2). In Na–Se batteries, the Se@VCF‐CNTs electrode with a Se loading of 5 mg cm−2 exhibits a discharge capacity of 436 mAh g−1 after 200 cycles, proving its consistent cycling performance. This study enriches the field of knowledge concerning high‐loading Se‐based battery systems, offering a promising avenue for enhancing energy density in the field. [ABSTRACT FROM AUTHOR]

The amount of As(III) adsorbed and the interfacial process are closely associated with the phase transformation of Schwertmannite (SCH). At present, studies on the adsorption characteristics of As(III) on SCH and the accompanying phase transformation process, especially the related mechanisms under the mediation of iron-reducing bacteria (FeRB) and sulfate-reducing bacteria (SRB), are limited in existing literature. With the help of continuous characterization, the adsorption behavior of As(III) on SCH was explored, as well as the transformation processes of SCH during these processes. The findings revealed that the SCH, synthesized by the KMnO4 oxidation and ethanol modification methods, exhibited excellent physical adsorption capacity for As(III) due to their increasing specific surface area and porosity. At room temperature (20°C), the saturation adsorption capacities of As(III) by M-SCH and Y-SCH reached 62.69 and 58.62 mg/g, respectively. Moreover, the generation and phase transformation of As(III)-bearing ferrihydrite were observed within a 60-min timeframe. It is the first time this phenomenon has been observed in such a short time, which is presumed to be an intermediate stage in the transformation of SCH into goethite. Furthermore, both FeRB and SRB could enhance the adsorption capacity of SCH for As(III). Comparatively, SRB has a more substantial impact on SCH's phase transformation. These insights are valuable for the practical application of SCH in treating As(III) pollution. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have recently become attractive candidate substrates for surface-enhanced Raman spectroscopy (SERS) owing to their atomically flat surfaces and adjustable electronic properties. Herein, large-scale 2D 1T′- and 2H-MoTe2 films were prepared using a chemical vapor deposition method. We found that phase structure plays an important role in the enhancement of the SERS performances of MoTe2 films. 1T′-MoTe2 films showed a strong SERS effect with a detection limit of 1 × 10−9 M for the R6G molecule, which is one order of magnitude lower than that of 2H-MoTe2 films. We demonstrated that the SERS sensitivity of MoTe2 films is derived from the efficient photoinduced charge transfer process between MoTe2 and adsorbed molecules. Moreover, a prohibited fish drug could be detected by using 1T′-MoTe2 films as SERS substrates. Our study paves the way to the development and application of high-performance SERS substrates based on TMD phase engineering. [ABSTRACT FROM AUTHOR]

Traditional mechanical processing of zirconium leads to an unfavorable transformation, from a metastable tetragonal phase to a monoclinic phase (t→m), which weakens the structure of the material and subsequently leads to damage to the prosthetic restoration. The aim of this research is to compare commonly used surface treatments to determine which has the least effect on t→m. Thirty cylindrical samples made of sintered zirconium were divided into six groups based on the following treatments: polishing, grinding, sandblasting, chemical etching, laser structuring or dry plasma etching. After surface treatment, the samples were subjected to the following tests: X-Ray Diffraction, microscopic examination, surface wettability and surface roughness measurements. Chemical etching, laser structuring and plasma etching significantly reduce the content of the monoclinic phase. All surface treatments significantly reduced the final amount of the monoclinic phase. However, chemical etching did not provide sufficient surface roughness. Both laser and plasma processing offer the advantage of creating structural patterns on the surface of elements. However, as plasma etching requires a mask to obtain the appropriate pattern on the surface, it seems that laser processing offers more and varied structuring possibilities. Laser structuring is easier to control and more economical than the other methods. [ABSTRACT FROM AUTHOR]

To examine the permeability alterations in coal seams induced by liquid CO2 injection, we employed COMSOL simulations to recreate the flow, force, and temperature fields, along with the corresponding physical parameters of the geological formation. We established a mathematical model to track the evolution of the coal body's permeability, enabling us to capture the phase distribution of CO2, the dynamics of fluid transportation, and the coal body's mechanical responses during the liquid CO2 injection process. Our findings revealed that the coal seam undergoes significant changes due to low-temperature freezing and shrinkage, gas-liquid phase transitions, and expansion impacts from solid-liquid phase changes. These factors collectively modify the pore structure, subsequently influencing the coal seam's permeability. Notably, the coal body's permeability, influenced by the pore structure and the Klinkenberg effect, increases logarithmically with rising injection pressure and falling temperatures. The structural changes in the coal body are markedly impacted by seepage and phase change pressures, with the permeability enhancement from secondary phase changes being 2.28 times greater than that from primary phase changes, and five times greater than in scenarios without phase change. [ABSTRACT FROM AUTHOR]

Pyrolusite comprises the foremost manganese oxides and is a major source of manganese production. An innovative hydrogen-based mineral phase transformation technology to pyrolusite was proposed, where a 96.44% distribution rate of divalent manganese (Mn2+) was observed at an optimal roasting temperature of 650°C, a roasting time of 25 min, and an H2 concentration of 20vol%; under these conditions. The manganese predominantly existed in the form of manganosite. This study investigated the generation mechanism of manganosite based on the reduction kinetics, phase transformation, and structural evolution of pyrolusite and revealed that high temperature improved the distribution rate, and the optimal kinetic model for the reaction was the random nucleation and growth model (reaction order, n = 3/2) with an activation energy (Ea) of 24.119 kJ·mol−1. Throughout the mineral phase transformation, manganese oxide from the outer layer of particles moves inward to the core. In addition, pyrolusite follows the reduction sequence of MnO2 → Mn2O3 → Mn3O4 → MnO, and the reduction of manganese oxides in each valence state simultaneously proceeds. These findings provide significant insight into the efficient and clean utilization of pyrolusite. [ABSTRACT FROM AUTHOR]

In China, large amounts of industrial byproduct gypsum (IBG) end up as waste and excessive stockpiling due to its low whiteness and high impurity content. In this study, two typical IBG including phosphogypsum (PG) and flue gas desulfurization gypsum (FGDG) were the research object. The impurities removal and the whiteness improvement by the tandem pyro-hydro process were investigated. Species of impurities, mechanism of whiteness improvement and the evolution of the gypsum phase during the tandem process were revealed. The results indicate that the impurities responsible for the poor whiteness of IBG included organic matter, carbon particles, and silicates. The temperature of the pyro process is the critical factor. The IBG is calcinated at 400–500 °C to fully remove organic matter and carbon particles, while decompose silicates to silica. Following, in the hydro step, the calcined IBG was treated with dilute sulfuric acid (0.2–1.0 M) to remove ion impurities such as Fe(III), the higher temperature and higher acidity are favorable to the production of valuable CaSO4. After treatment, the whiteness of IBG was improved from below 40% to above 80%, and the soluble impurity content can meet the standards. Moreover, both PG and FGDG products exhibited a compressive strength exceeding 10.0 MPa of curing for 7 d. This work provides theoretical guidance to promote the resource utilization of IBG, especially as plastering materials after purification and whitening. [ABSTRACT FROM AUTHOR]

The solidification process and uniaxial tensile test of Al–Cu–Mg alloy at the atomic scale were studied using the molecular dynamics method. The influence of the Mg/Cu ratio on the microstructure and mechanical properties of the Al–Cu–Mg alloy was investigated. The results indicated that during the solidification, the diffusion coefficient of Mg atoms was the lowest, while that of Al atoms was the highest. There may be strong bonding and strong chemical short range ordered structures between Mg–Mg, Al–Cu, and Mg–Cu atoms. As the uniaxial tensile progressed, the alloy exhibited a transformation of FCC→BCC→HCP phase. With increase of the Mg/Cu ratio, HCP and FCC layer-like phases gradually appeared, promoting the occurrence of twins and stacking faults, which resulted in dislocation slip and stress relaxation. As a result, the material become more prone to deformation, leading to a reduction in tensile strength. [ABSTRACT FROM AUTHOR]

ABSTRACT Microwave heating is an intriguing method for the synthesis of inorganic solids offering a variety of advantages over conventional furnace heating, such as fast heating and cooling rates as well as volumetric and selective heating of precursors. However, there are many open questions regarding this “black‐box” process, and insights into the effect of microwave radiation on different types of solids are generally missing. In situ Raman spectroscopy is a powerful technique to unravel chemical transformations and identify intermediate species during microwave solid‐state syntheses. A major challenge is the temperature measurement under microwave conditions because (metallic) thermocouples cannot be used and optical pyrometry has significant drawbacks. In contrast, Raman thermometry is a viable method that relies on the temperature‐induced shift of Raman signals. Here, we use this method to estimate the temperature during microwave heating of a model system (titania) that undergoes a phase transition at temperatures >800°C. The estimation is derived from a flexible double exponential calibration function applied to Raman spectroscopic peak shifts in the temperature‐resolved furnace heating data, which was found to describe two titania modes (one anatase and one rutile) extremely well. Based on a detailed error and uncertainty analysis, we suggest options to further optimize Raman thermometry for use in high‐temperature microwave heating conditions. [ABSTRACT FROM AUTHOR]

Cr 2 Mo 3 O 12 ceramics show negative thermal expansion (NTE) in a narrow high-temperature range due to the phase transition around 385 °C. To widen its NTE temperature range, a series of (NaMg)3+ co-doped Cr 2 Mo 3 O 12 ceramics has been synthesized via a solid reaction process in this work. The effects of double cation (NaMg)3+ co-doping on the phase composition, morphology, phase transformation, and thermal expansion performance of Cr 2 Mo 3 O 12 ceramics were studied using XRD, Raman, XPS, SEM, and TMA. Results indicate that double cation (NaMg)3+ can partially substitute Cr3+ in Cr 2 Mo 3 O 12 , which causes a phase transition from monoclinic Cr 2 Mo 3 O 12 to hexagonal (NaMg) x Cr 2-x Mo 3 O 12. The single-phase (NaMg) x Cr 2-x Mo 3 O 12 ceramics with hexagonal structure is obtained when x = 0.5. (NaMg)3+ co-doping promotes the growth of grains and the density of hexagonal (NaMg) 0·5 Cr 1·5 Mo 3 O 12 ceramics. (NaMg)3+ co-doping also successfully eliminates the temperature-induced phase transition of Cr 2 Mo 3 O 12 at 385 °C. Hexagonal (NaMg) 0·5 Cr 1·5 Mo 3 O 12 ceramics presents a better NTE with a coefficient of thermal expansion (CTE) of −3.97 × 10−6 °C−1 over a larger temperature range from 30 °C to 700 °C. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cesium lead iodide (CsPbI3) exhibits great potential in developing photovoltaic cells due to suitable optical bandgap and thermal stability. However, the photoactive γ‐phase normally exists at high‐temperatures ≈180 °C, and it is challenging to obtain γ‐phase CsPbI3 at room temperature. Here, it discovers that γ‐phase CsPbI3 is achievable by reducing the underlayer surface roughness to a certain level. This method is universal as demonstrated on the surface of poly(3,4‐ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS), poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA), polystyrene (PS), and silicon substrates. Moreover, it is found that lower surface roughness resulted in smaller crystallite size in the CsPbI3 film, which is an important reason for achieving γ‐phase because the decrease in crystallite size will increase grain surface energy to suppress tilting of PbI6 octahedra and lattice distortion. This study offers a universal approach to obtain γ‐phase CsPbI3 for the development of high‐performance all‐inorganic perovskite solar cells and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Overcoming the hardness‐toughness trade‐off in diamonds attracts much interest in physics, chemistry, materials science, and engineering. Recently synthesized nanotwinned diamond composite exhibits massive enhancement in fracture toughness without sacrificing its unprecedented Vickers hardness [Y. Yue et al., Nature 582, 370 (2020)]. Several mechanisms for the toughness enhancement are unveiled based on the edge‐cracked models while the mechanism from Vickers indentation has remained elusive. Here, the energy of nanotwinned diamonds, diamond polytypes, and diamond composites is systematically investigated from Vickers indentation simulation. The results show diamond structures dissipate energy by interface migration, accompanied by the phase transformation from diamond polytypes to the cubic diamond (3C diamond). By tuning the density and distribution of interfaces, the dissipated energy of the diamond is increased to more than twice that of a single‐crystal 3C diamond. This work complements the established mechanisms and provides a universal strategy for toughening diamonds and related materials. [ABSTRACT FROM AUTHOR]

A new type of SiCf/TiC-Ti3SiC2 composite was prepared by the Spark Plasma Sintering (SPS) method in this work. The phase transformation and interface cracking of this composite under ion irradiation (single Xe, Xe + He, and Xe + He + H ions) and subsequent annealing were analyzed using transmission electron microscopy (TEM), mainly focusing on the interface regions. Xe ion irradiation resulted in the formation of high-density stacking faults in the TiC coatings and the complete amorphization of SiC fibers. The implanted H ions exacerbated interface coarsening. After annealing at 900 °C for 2 h, the interface in the Xe + He + H ion-irradiated samples was seriously damaged, resulting in the formation of large bubbles and cracks. This damage occurred because the H atoms reduced the surface free energy, thereby promoting the nucleation and growth of bubbles. Due to the absorption effect of the SiCf/TiC interface on defects, the SiC fiber areas near the interface recovered back to the initial nano-polycrystalline structure after annealing. [ABSTRACT FROM AUTHOR]

The porous Ti/perovskite composites were prepared successfully by ultrasound-assisted infiltration method. The Cs–Pb–Br perovskite materials were prepared on a larger scale by the mechanical ball-milling using the CsBr and PbBr 2 as the precursors. The Cs–Pb–Br perovskites had high PL intensity and excellent stability, meanwhile, the complex phase transformation between CsPbBr 3 and Cs 4 PbBr 6 occurred during the ball-milling process. The green fluorescence emission of composites might be attributed to CsPbBr 3 embedded within Cs 4 PbBr 6 perovskite. By the space occupying method, the porous Ti materials were prepared by using the acicular urea as the pore forming. The optimal young's modulus (1.0851 GPa) and porosity (38.27 %) were obtained. Finally, the prepared Ti/perovskite composites had outstanding fluorescence property and high stability, showing the wide application prospect in the fields of the bioflourescence imaging and nondestructive testing fields. [ABSTRACT FROM AUTHOR]

Phase engineering is considered an effective strategy to regulate the electrocatalytic activity of catalysts for Li–S batteries (LSBs). However, the underlying origin of phase‐dependent catalytic ability remains to be determined, which significantly impedes the design principles of high‐performance catalytic materials for LSBs. Herein, heteroatom‐doped engineering can trigger phase transformation from mixed‐phased cubic and orthorhombic cobalt diselenide into pure orthorhombic structure with a tensile strain and enhanced charge localization. The upshift of the d‐band center and enhanced Bader charge at Se sites synergistically strengthen the interaction with Li and S sites in polysulfide species, thus endowing the transformed P‐MoSe2/MXene with high catalytic activity and uniform lithium deposition for LSBs. Consequently, the P‐CoSe2/MXene Li–S batteries demonstrate a high‐rate capability of 603 mAh g−1 at 4C, and an excellent cyclability of 652 mAh g−1 at 1C over 500 cycles with a degradation rate of 0.076% per cycle. The work provides an in‐depth insight into the fundamental design principles of effective catalysts for LSBs. [ABSTRACT FROM AUTHOR]

The development of smart synthetic materials that are sensitive, accurate, and visually responsive to changes in temperature is vital. Herein, a supramolecular luminescent hydrogel based on a glycine/terbium (Gly/Tb) complex, rhodamine B (RB), and gelatin is reported. The hydrogel exhibits responsive luminescence and undergoes a temperature‐induced phase transformation from hydrogel to sol. The electrospray ionization time‐of‐flight mass spectra, Fourier‐transform infrared spectra, and simulation results verifiy the coordination mode of the Gly/Tb complex. The Gly/Tb complex and RB emit green and orange luminescence, respectively. When the Gly/Tb complex and RB are co‐doped into the gel network of gelatin, the obtained Gly/Tb/RB hydrogel displays steady yellow luminescence by virtue of luminescence resonance energy transfer. Subsequently, a luminescent switch is constructed owing to the sensitive and reversible luminescence responsiveness of the Gly/Tb/RB hydrogel to temperature stimuli. Remarkably, the Gly/Tb/RB hydrogel undergoes a visual phase transformation from hydrogel to sol above 35 °C, allowing the ambient temperature variation to be monitored. This study establishes a novel and effective route for the construction of smart optical materials and visual temperature monitors. [ABSTRACT FROM AUTHOR]

The increased coefficient of thermal expansion (CTE) mismatch and mechanical performance degradation of glass‐based sealant‐induced thermal stress are critical issues for long‐term application of solid oxide fuel cell (SOFC). In this work, the double effect of MgO particle on dispersion strengthening, inhibition low‐CTE phase transformation, thermal stress, and leakage rate in BaO‒CaO‒Al2O3‒B2O3‒SiO2 (BCABS) glass‐ceramic were investigated and analyzed. The low‐CTE mono‐BaAl2Si2O8 phase was suppressed by the MgO particle reacting with BCABS glass‐ceramic. Consequently, the CTE for BCABS glass‐ceramic without MgO decreases from 11.47 at 1 h to 10.18 ×10−6/°C at 1000 h and reduction rate is higher than 10%, bring about the thermal stress of sealant itself and interface had tripled (200 MPa) and leakage rate was high than 0.06 sccm/cm after 250 h. However, the CTE of 20 wt% MgO‐reinforced BCABS glass‐ceramic sealant only declined about 4.0% for 1000 h, resulting in slow increase or even decrease in the thermal stress (low than 60 MPa) and maintaining stable leakage rate below 0.04 sccm/cm for 1000 h with three thermal cycles. This study was useful for identifying optimal CTE matching and elastic modulus of glass‐based sealant for efficient and stable long‐term operation of SOFC. [ABSTRACT FROM AUTHOR]

While zirconia implants exhibit osseointegration comparable to that of titanium, concerns arise regarding low-temperature degradation and its potential impact on fracture strength. This study investigated the phase transformation and fracture characteristics of zirconia dental implants after aging through chewing simulation and subsequent static loading. The experimental setup involved 48 one-piece monobloc zirconia implants with diameters of 3.0 mm and 3.7 mm that had straight or angled abutments, with crown restorations, which were divided into six groups based on intraoral regions. The specimens underwent chewing simulation equal to five years of oral service, which was followed by static loading. Statistical analyses were performed for the data obtained from the tests. After dynamic and static loadings, the fractured samples were investigated by Raman spectroscopy to analyze the phase composition and micro-CT to evaluate fracture surfaces and volume changes. According to the results, narrow-diameter zirconia implants have low mechanical durability. The fracture levels, fracture patterns, total porosity, and implant fracture volume values varied according to the implant diameter and phase transformation grade. It was concluded that phase transformation initially guides the propagation of microcracks in zirconia implants, enhancing fracture toughness up to a specific threshold; however, beyond that point, it leads to destructive consequences. [ABSTRACT FROM AUTHOR]

α+β dual phase Ti-(0~6 wt.%) Fe alloys were prepared via sintering and hot rolling process to clarify the effects of Fe contents and the rolling temperature on their microstructures and crystalline orientation. With an increase in the Fe content, the volumetric fraction of the β-Ti phase, contains high Fe solutes, drastically increased. When hot rolled at 750°C (α+β dual-phase temperature), each phase grew immediately after rolling and suppressed each other’s grain growth, resulting in fine microstructure formation and uniform residual strain. In Ti-Fe alloys rolled at 1000°C (single β-phase temperature), a very small amount of residual strain was observed, and acicular α-Ti grains with random crystalline orientations were formed due to the phase transformation from β-Ti grains after rolling. [ABSTRACT FROM AUTHOR]

This research investigates the effect of silicon (Si) addition on the phase transformation behaviour of the Ni–Ti alloy. The Ni–Ti–Si alloys were fabricated with varying proportions of Si through a modified vacuum induction melting technique with argon backfilling. Scanning electron microscopy, X-ray diffraction and differential scanning calorimetry were done to analyse the microstructure, elemental composition, and phase transformation temperatures, respectively, to validate the effectiveness of this modified melting technique. The results indicate an increase in the phase transformation temperature with an increase in the Si content in the alloy mixture and the alloys were prepared with a very minimal amount of detrimental impurities. This technique helps to produce high-temperature shape memory alloys with utmost purity which helps in retaining their functional properties. The transformation temperatures observed from differential scanning calorimetry revealed that the Af temperature varies from 342.68 K to 379.95 K for 3 to 12% variation in Si content. This group of shape memory alloys have potential use as actuators in aircrafts and various other applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mn6Ni16Si7 intermetallic compounds, referred to as the G phase, and their precursors are recognized as potential secondary phases precipitated in neutron-irradiated steels and are the main cause of embrittlement in low-alloyed reactor pressure vessel steels under long-term operation. To obtain the mechanical properties and thermal stability of the G phase, two Mn-Ni-Si model alloys (composed of 21 mol%Mn-58 mol%Ni-21 mol%Si and 30 mol%Mn-58 mol%Ni-12 mol%Si) were annealed at 1,000°C. The existence of the G phase in both annealed ternary model alloys was confirmed by XRD and SEM/EDS. Meanwhile, the process of different Mn-Ni-Si ternary regions to the G phase transformation under 1,000°C annealing has also been discussed. Young's modulus and nano-hardness of the G phase were measured using the nanoindentation technique. The results showed similar values for the G phase in two alloys with Young's modulus of approximately 220 GPa, which is similar to Young's modulus of iron. This fact suggests the necessity of reconsideration of the hardening model contributed by G phase precipitates in reactor pressure vessels in the future. [ABSTRACT FROM AUTHOR]

In the present study, the effect of the Nb element on the lattice parameters, phase stability and martensitic transformation behaviors of Ti-Zr-based shape memory alloys was extensively investigated using the first-principles calculation. The lattice parameters of both the β parent phase and α′ martensite phase gradually decreased with Nb content increasing. For the α″ martensite phase, the lattice constant (a) gradually increased with the increase in Nb content, whereas the lattice constants (b and c) continuously decreased due to the addition of Nb. Based on the formation energy and density of state, β→α′ martensitic transformation occurred, as the Nb content was not more than 12.5 at.%. However, the Ti-Zr-Nb shape memory alloys with a Nb content higher than 12.5 at.% possessed the β→α″ martensitic transformation. However, both the largest transformation strain and sensitivity of critical stress to temperature (dσ/dT) can be optimized by controlling 12.5 at.% Nb in the Ti-Zr-Nb shape memory alloy, which was favorable to obtaining the largest elastocaloric effect. [ABSTRACT FROM AUTHOR]

Laser Hot Wire (LHW) Directed Energy Deposition (DED) Additive Manufacturing (AM) processes are capable of manufacturing parts with a high deposition rate. There is a growing research interest in replacing large cast Nickel Aluminum Bronze (NAB) components using LHW DED processes for maritime applications. Understanding thermomechanical behavior during LHW DED of NAB is a critical step towards the production of high-quality NAB parts with desired performance and properties. In this paper, finite element simulations are first used to predict the thermomechanical time histories during LHW DED of NAB test coupons with an increasing geometric complexity, including single-layer and multilayer depositions. Simulation results are experimentally validated through in situ measurements of temperatures at multiple locations in the substrate as well as displacement at the free end of the substrate during and immediately following the deposition process. The results in this paper demonstrate that the finite element predictions have good agreement with the experimental measurements of both temperature and distortion history. The maximum prediction error for temperature is 5% for single-layer samples and 6% for multilayer samples, while the distortion prediction error is about 12% for single-layer samples and less than 4% for multilayer samples. In addition, this study shows the effectiveness of including a stress relaxation temperature at 500 °C during FE modeling to allow for better prediction of the low cross-layer accumulation of distortion in multilayer deposition of NAB. [ABSTRACT FROM AUTHOR]

Copper smelting slag is a significant potential resource for cobalt and copper. The recovery of copper and cobalt from copper slag could significantly augment the supply of these metals, which are essential to facilitating the transition to green energy while simultaneously addressing environmental concerns regarding slag disposal. However, the complex mineral composition of copper slag poses an enormous challenge. This study investigated the mineralogical and chemical characteristics of copper slag, which are vital for devising the most effective processing techniques. XRD and FESEM-EDS were employed to examine the morphologies of copper slag before and after the reduction process. The effects of borax and charcoal (carbocatalytic) reduction on phase transformation were evaluated. The XRD analysis revealed that the primary phases in the copper slag were Fe2SiO4 and Fe3O4. The FESEM-EDS analysis verified the presence of these phases and yielded supplementary details regarding metal embedment in the Fe2SiO4, Fe3O4, and Cu phases. The carbocatalytic reduction process expedited the transformation of copper slag microstructures from crystalline dendritic to amorphous and metallic phases. Finally, leaching experiments demonstrated the potential benefits of carbocatalytic reduction by yielding high extractions of Cu, Co, and Fe. [ABSTRACT FROM AUTHOR]

42CrMo4-type steel grades are widely used in a great variety of components that require ad hoc mechanical properties. However, due to the dimensions of large components and the previous thermomechanical treatments, the presence of heterogeneities in the chemical compositions are expected to impact those mechanical properties. In the present work, a detailed analysis of phase transformation behavior upon cooling was carried out through a dilatometry test on samples of 42CrMo4 belonging to a component that has a non-homogeneous chemical distribution. The analysis of the dilatation signals and the quantitative metallography shows a rather complex behavior depending on the cooling rate as well as on the region of observation. Two different phase transformation models based on Li's approach were applied to the present composition to determine the CCT curve as well as the fraction of the microconstituents. An extensive discussion was carried out on some aspects about Kirkaldy-based approaches that need to be improved so as to attain more reliable quantitative results when modeling phase transformations in heterogenous systems. [ABSTRACT FROM AUTHOR]

Visible‐light active anatase/brookite/rutile (A/B/R) ternary N‐doped titania (N/TiO2) crystals are successfully prepared by a facile sol‐gel method using titanium butoxide and benign N‐dopant source, guanidinium chloride. Systematically varying the aging time (1, 4, 8, and 12 d), its influence on physicochemical properties of as‐obtained spherical heterojunction nanomaterials is studied. Detailed characterizations confirm that a substantial amount of anatase (88% to 50%) is transformed to rutile (2% to 38%) via intermediate brookite phase (9% to 25%) as the function of aging time; not only the A/B/R phase content of the samples is tuned by sol‐gel aging time of the precursors solution but also their optical‐response and methylene blue photocatalytic properties are profoundly dictated. Notably under visible‐light irradiation, the photostable rutile rich mesoporous A/B/R triphasic N/TiO2 (50% A, 12% B, 38% R) aged for 12 d demonstrates higher degradation activity (97%) with a faster degradation rate (0.033 min−1) than both lesser aged N/TiO2 and undoped titania. This enhancement is attributed to the synergistic effect of interstitial‐N‐doping and optimal A/B/R interfacial charge transfer that leads to higher light absorption, lower bandgap energy and well‐separated charge carriers. The current work provides a new perspective for designing highly active visible‐light heterostructure nanomaterials with controllable phase composition. [ABSTRACT FROM AUTHOR]

The microstructure, phase composition and elemental composition in the α- and β-phases of the two-phase wrought Ti-5.7Al-1.6V-3Mo titanium alloy at room temperature were studied by transmission electron microscopy and X-ray energy-dispersive spectroscopy. The temperature ranges of phase transformations in the alloy during heating from 298 to 1523 K were studied by differential scanning calorimetry (DSC). Two endothermic peaks were observed on the DSC curve at the temperatures of 1078 K and 1207 K, and one exothermic peak was observed at a temperature of 1123 K. The endothermic peak on the DSC curve at a temperature of 1078 K is due to the formation of α″-martensite, at a temperature of 1207 K is caused by α → β phase transformation. The exothermic peak at a temperature of 1123 K, presumably, corresponds to the polymorphic transformation of brookite → rutile in TiO2 oxide. High-temperature synchrotron studies were carried out from room temperature to 1373 K. It was found that the increase in lattice parameters during heating is nonlinear. Possible mechanisms of the nonlinear change in the lattice parameters at temperatures above 1200 K are discussed. At T > 1000 K α″-martensite was formed by β → α″ phase transformation. An increase in the volume fraction of α″-phase with increase in temperature was accompanied by a decrease in the volume fraction of β-phase. An increase in microstrain of the α-phase lattice and a decrease in microstrain of the β-phase lattice were observed upon heating. [ABSTRACT FROM AUTHOR]

The continuous phase transition phenomena and mechanism of pellets in the hydrogen blast furnace is achieved by dissecting the 40m3 hydrogen blast furnace. The results of the dissection reveal that the lumpy zone extends to the bosh of the hydrogen blast furnace (HBF), while it ends at about 2/3 of the stack in traditional blast furnace. The iron oxide (FeO x) began to appear in the upper stack, while the iron started to appear in the lower stack. The reduction rate and metallization rate at the bosh are measured at 95.18% and 95.54%. The content of ferrous oxide (FeO) decreases significantly (measured at 1.73% at the bosh), resulting in an increase in the melting point of the primary slag and a deterioration of its fluidity. FeO x formed in the upper stack continuously diffuses and merges into the gangue, which affects the subsequent transformation of FeO x. FeO x shows a preference for interacting with SiO 2 , CaO, and MgO, directly influencing the formation of slag in the cohesive zone. These findings offer valuable insights for numerical simulation and research on hydrogen-rich operation. • A 40 m3 experimental hydrogen-rich blast furnace is dissected. • The lumpy zone of hydrogen blast furnace extends to bosh. • The reduction rate and metallization rate at the bosh are 95.18% and 95.54%. • FeO x tends to react with SiO 2 to form high melting point substance. • A mechanism of iron and gangue transformation is proposed. [ABSTRACT FROM AUTHOR]

Buildings, accounting for approximately 40% of global energy consumption, heavily rely on windows for maintaining indoor comfort. However, conventional windows are known for their inefficiency due to high optical transmittance and thermal conductivity. In recent decades, efforts have focused on enhancing sustainability through the development of low-emissivity coatings and smart windows. Despite advancements, the commercialization of a vanadium dioxide (VO2) nanostructure-based thermochromic film has been limited by stability issues. This study addresses the critical need for long-term stability and efficiency in VO2-based smart windows, showcasing a composite film that is highly resilient to heat, ultraviolet (UV) light, and humidity. The proposed films exhibit exceptional solar energy regulation capability (ΔTsol = 20.11%) alongside a visible light transmittance of 54.94%. Moreover, they exhibit strong stability even under conditions of high relative humidity (90%) and temperature (60 °C), maintaining consistent phase-transition performance over 40 daysequivalent to approximately 1777 days of real-world exposure. Impressively, even without encapsulation, the composite film retains 96.4% of its initial ΔTsol after continuous 60-day illumination. This research offers promising technical solutions for advancing the commercial viability of traditional VO2 smart windows, contributing significantly to global efforts toward carbon neutrality and sustainable development. [ABSTRACT FROM AUTHOR]

The controllable α/β ratio of Si 3 N 4 powder was synthesized using tetraethyl orthosilicate (TEOS), glucose, MgCl 2 and YCl 3 ·6H 2 O by sol-gel assisted carbothermal reduction and nitridation (CRN). This study aimed to investigate the impact of various parameters, including a H 2 O/TEOS mol ratio of the sol, a C/Si mol ratio, sintering aids, and the temperature of CRN on the phase transformation of α-Si 3 N 4. The results demonstrated that the H 2 O/TEOS ratio significantly influenced the relative content of α and β phase in Si 3 N 4 by changing the morphological characteristics of SiO 2. When the H 2 O/TEOS ratio was 100, β-Si 3 N 4 powder with an approximate β content over 88 wt% was synthesized at 1500 °C. This remarkable phase transformation was likely facilitated by the eutectic liquid phase consisting of MgSiO 3 /Mg 2 SiO 4. The SEM image revealed rod-like whiskers with a length around 1.4 μm for the β-Si 3 N 4 grains. Due to the presence of liquid phase, the synthesis of spherical-like α-Si 3 N 4 nano-powder with an α-phase content of 91 wt% was achieved at a lower temperature of 1450 °C, with an H 2 O/TEOS ratio of 15 and a C/Si ratio of 4. The size of the particles was about 70 nm due to the reduced reaction temperature. Furthermore, without the addition of any sintering aids or Si 3 N 4 seeds, high purity α-Si 3 N 4 with an α phase content approaching 96 wt% could be synthesized at 1500 °C, using an H 2 O/TEOS ratio of 15 and a C/Si ratio of 4. The resulting α-Si 3 N 4 powder exhibited an extremely regular hexagonal prism shape with a length of approximately 2 μm. [Display omitted] [ABSTRACT FROM AUTHOR]

This study employs the finite element method to investigate the microstructural evolution and deformation behavior of a 40Cr steel automobile front axle during the quenching process. By establishing a multi-physics field coupling model, the study elucidates the variation patterns of the microstructure field in the quenching process of the front axle under different immersion orientations. It is found that along the length direction, the bainite and martensite structures decrease from the center to the edge region, while the ferrite structure shows an increasing trend. Additionally, the influence of immersion orientation on the hardness of the front axle's microstructure and deformation behavior is thoroughly discussed. The results indicate that, firstly, when quenched horizontally, the hardness difference among different regions of the front axle is approximately 8.2 HRC, whereas it reaches 10.3 HRC when quenched vertically. Considering the uniformity of the microstructure, the horizontal immersion method is preferable. Secondly, due to the different immersion sequences in different regions of the front axle leading to varying heat transfer rates, as well as the different amounts of martensite structures obtained in different regions, the deformation decreases along the length direction from the center to the edge region. Horizontal immersion quenching, compared to vertical immersion, results in a reduction of approximately 56.2% and 48.9% in deformation on the representative central cross-section (A-A) and the total length of the front axle, respectively. Therefore, considering aspects such as microstructure uniformity and deformation, the horizontal immersion quenching orientation is more favorable. [ABSTRACT FROM AUTHOR]

Continuous casting is the most common method for producing steel into semi-finished shapes like billets or slabs. Throughout this process, steel experiences mechanical and thermal stresses, which influence its mechanical properties. During continuous casting, decreased formability in steel components leads to crack formation and failure. One reason for this phenomenon is the appearance of the soft ferrite phase during cooling. However, it is unclear under which conditions this ferrite is detrimental to the formability. In the present research, we investigated what microstructural changes decrease the formability of microalloyed steels during continuous casting. We studied the hot compression behaviour of microalloyed steel over temperatures ranging from 650 °C to 1100 °C and strain rates of 0.1 s − 1 to 0.001 s − 1 using a Gleeble 3800® (Dynamic Systems Inc, Poestenkill, NY, USA) device. We examined microstructural changes at various deformation conditions using microscopy. Furthermore, we implemented a physically-based model to describe the deformation of austenite and ferrite. The model describes the work hardening and dynamic restoration mechanisms, i.e., discontinuous dynamic recrystallisation in austenite and dynamic recovery in ferrite and austenite. The model considers the stress, strain, and strain rate distribution between phases by describing the dynamic phase transformation during the deformation in iso-work conditions. Increasing the strain rate below the transformation temperature improves hot ductility by reducing dynamic recovery and strain concentration in ferrite. Due to limited grain boundary sliding, the hot ductility improves at lower temperatures (<750 °C). In the single-phase domain, dynamic recrystallisation improves the hot ductility provided that fracture occurs at strains in which dynamic recrystallisation advances. However, at very low strain rates, the ductility decreases due to prolonged time for grain boundary sliding and crack propagation. [ABSTRACT FROM AUTHOR]

In this study, microstructure, mechanical, and shape memory properties of the welded Fe-based shape memory alloy (Fe-SMA) plates with a nominal composition of Fe-17Mn-5Si-10Cr-4Ni-(V, C) (wt.%) by gas tungsten arc welding were investigated. The optimal heat input to ensure full penetration of the Fe-SMA plate with a thickness of 2 mm was found to be 0.12 kJ. The solidified grain morphology adjacent to the partially melted zone was columnar, whereas the equiaxed morphology emerged as solidification proceeded. The ultimate tensile decreased after welding owing to the much larger grain size of the fusion zone (FZ) and heat-affected zone (HAZ) than that of the base material (BM). Weldment showed lower pseudoelastic (PE) recovery strain and higher shape memory effect (SME) than those of the plate, which could be ascribed to the large grain size of the FZ and HAZ. Recovery stress (RS) slightly decreased after welding owing to lower mechanical properties of weldment. On the other hand, aging treatment significantly improved all PE recovery, SME, and RS via carbide precipitation. Digital image correlation analysis revealed that HAZ showed the lowest SME after heating and cooling, implying that the improved SME of FZ compensated for the low SME of the HAZ. [ABSTRACT FROM AUTHOR]

The kinetics of phase transformations in the nitriding process α-Fe → γ'-Fe4N → ε-Fe3-2N of the pre-reduced iron ammonia synthesis catalyst was investigated under in situ conditions (atmospheric pressure, 350 °C) by measuring changes of mass, gas phase composition, and magnetic permeability in a differential tubular reactor. The iron nanocrystallite size distribution according to their specific active surface areas was measured, and it was found that the catalyst is bimodal as the sum of two Gaussian distributions, also differing in the value of the relative magnetic permeability. Relative magnetic permeability of small α-Fe crystals in relation to large crystals is higher by 0.02. In the area of α → γ' transformation, the magnetic permeability dependencies change, proving the existence of two mechanisms of the α-Fe structure change in the α-Fe → γ'-Fe4N transformation. In the first area, a solution of α-Fe (N) is formed with a continuous and insignificant change of the crystal lattice parameters of the iron lattice. In the second area, there is a step, oscillatory change in the parameters of the iron crystal lattice in FexN (x = 0.15, 0.20, 0.25 mol/mol). In the range of γ'-Fe4N → ε-Fe3-2N transformation, a solution is formed, with nitrogen concentration varying from 0.25–0.45 mol/mol. During the final stage of the nitriding process, at a constant value of the relative magnetic permeability, only the concentration of nitrogen in the solution εr increases. The rate of the phenomenon studied is limited by a diffusion rate through the top layer of atoms on the surface of iron nanocrystallite. The estimated value of the nitrogen diffusion coefficient varied exponentially with the degree of nitriding. In the area of the solution, the diffusion coefficient is approximately constant and amounts to 5 nm2/s. In the area of oscillatory changes, the average diffusion coefficient changes in the range of 3–11 nm2/s, and is inversely proportional to the nitrogen content degree. The advantage of the research method proposed in this paper is the possibility of simultaneously recording, under reaction conditions, changes in the values of several process parameters necessary to describe the process. The research results obtained in this way can be used to develop such fields of knowledge as heterogeneous catalysis, materials engineering, sensorics, etc. [ABSTRACT FROM AUTHOR]

Surface modification of SS-316L using an organic and inorganic hybrid coating of polymethyl methacrylate (PMMA) and silicon dioxide (SiO2) is being conducted in the current investigation with crosslinking agent 3-aminopropyl tri-ethoxy silane (APTES). The solvent-gel method and dip coating with varying amount of SiO2 (i.e. 0.5, 1, and 1.5 wt.%) is used for surface modification. On the coated surface, Fourier transform infrared spectroscopy (FTIR) at 1000–1250 cm−1 reveals the crosslinking of silicon and PMMA. The coatings formed on SS-316L are homogenous, transparent, and free of defects and voids when seen macroscopically. A good crystallinity and presence of coated material can be seen from the X-ray diffraction and microstructure analysis of coated surface. The PMMA coating with 1.5 wt.% SiO2 has the most apatite crystals deposited on surface as observed with 7 days of immersion on simulated body fluid (SBF). These findings provide a solid link that coating SS-316L with SiO2 promotes bone bioactivity, and the PMMA+1.5 wt.% SiO2 coating can be employed on implants. The results of this study suggest a sustainable coating solution for improved bioactivity in medical applications and surgical instruments. [ABSTRACT FROM AUTHOR]

In-vessel retention (IVR) constitutes a pivotal strategy aimed at ensuring the structural integrity of the reactor pressure vessel (RPV). The lower cylinder is subjected to a high-temperature gradient, and the main failure mode of the RPV under IVR condition is attributed to multiaxial creep. At elevated temperatures, the pressure vessel steel 16MND5 undergoes a phase transformation from bainite to austenite, which significantly affects its creep behavior. The phase transformation temperature is distributed across the RPV wall thickness under the accident condition. Therefore, this study undertakes a comparative investigation of the macro- and micro-creep behavior of 16MND5 steel at pre- and post-phase transformation. The phase transformation temperature of the 16MND5 steel is determined to be 1024 K. Localized ablation and peeling of the RPV wall induce structural discontinuity, resulting in multi-axial stress. Accordingly, round bar specimens featuring varying U-notches were utilized for multi-axial creep test, and compared with uniaxial creep tests. Furthermore, the multi-axial creep stress of 16MND5 steel was analyzed by using finite element method, while the creep life was predicted by "skeletal-point stress method". A good agreement is achieved between theoretical and experimental results. [ABSTRACT FROM AUTHOR]

Pd‐based alloy nanomaterials normally crystallize in the conventional face‐centered cubic (fcc) crystal phase. Here, 2H‐Au nanosheets (NSs), possessing 2H crystal phase (2H: hexagonal close‐packed with a stacking sequence of “AB”), are used as templates for the growth of PdFe, during which the 2H‐to‐fcc phase transformation in Au NSs happens, leading to the formation of 2H/fcc Au@PdFe core–shell NSs. By changing the Pd/Fe atomic ratio, the 2H/fcc phase ratio in 2H/fcc Au@PdFe NSs can be tuned accordingly. As a proof‐of‐concept application, the as‐synthesized 2H/fcc Au@Pd0.66Fe0.34 NSs are used as an electrocatalyst for methanol oxidation reaction (MOR) in alkaline media, exhibiting a remarkable mass activity of 4.39 A mg−1Pd, which is 1.7, 5.4 and 12.9 times that of 2H/fcc Au@Pd0.56Fe0.44 NSs (2.57 A mg−1Pd), 2H/fcc Au@Pd0.40Fe0.60 NSs (0.81 A mg−1Pd), and Pd black (0.34 A mg−1Pd), respectively, placing it among the best of reported Pd‐based MOR electrocatalysts. This strategy, based on phase engineering of nanomaterials (PEN), paves an efficient way to the rational design and controlled synthesis of noble multimetallic nanostructures with unconventional phases for exploring the phase‐dependent properties and applications. [ABSTRACT FROM AUTHOR]

The increasing attention on high-entropy alloys (HEAs) stems from their distinctive properties, with particular emphasis on the remarkable hydrogen storage capacity of body-centered cubic (BCC) structured HEAs. This study investigates the microstructural evolution, thermal stability, and hydrogen storage behavior of as-milled Ti 5+x V 35 (CrMnFe) 60-x (x = 0,10,20,30) high-entropy alloys (HEAs) before and after heat treatment (HT). The microstructural characterization of the ball-milled HEAs reveals the presence of primary BCC and minor amounts of C14 Laves, with the proportion of C14 Laves gradually increasing with increasing Ti content. The hydrogen absorption capacity of the x = 30 alloy at room temperature is measured at 1.21 wt%, with a desorption capacity of 0.336 wt%. The phase stability of the alloys after HT depends on the Ti content, with the microstructure maintaining a nanoscale even after HT at 900 °C. The reduction in the BCC lattice constant after HT (x = 30) and synergistic effects among different phases (Laves and FCC), the hydrogen storage capacity decreases to 1.10 wt%, while desorption capacity slightly increases to 0.46 wt%. These findings elucidate the influence of mechanical alloying and HT on the microstructure and hydrogen storage performance of high-entropy alloys. • The HEAs at x = 30 show the highest hydrogen absorption capacity (1.21 wt%), and desorption capacity after HT (0.46 wt%). • With increasing Ti content in the as-milled state, the proportion of the C14 Laves gradually increases. • The HEAs retains nanocrystalline structure after HT at 900 °C. • Complex phase transformed in the HEAs (BCC + Laves-1.→BCC + FCC + Laves-1→BCC + FCC + Laves-1+Laves-2) during the HT. [ABSTRACT FROM AUTHOR]

Multiferroics with compositions BiFeO3, Bi0.90Ho0.10FeO3 and BiFe0.90Ho0.10O3 have been successfully prepared by solid-state reaction method. The structural analysis of Ho-substituted BiFeO3 affirms that the compounds are crystallized under rhombohedral perovskite structure with space group $R\overline 3 c$ R 3 ¯ c along with non-perovskite Bi2Fe4O9 phase. Cuboidal-shaped grains are observed in the micrographs of the Ho-substituted BiFeO3 sample with Ho at the Fe site. The changes in electrical and dielectric parameters with Ho substitution at the A-/B-site of BiFeO3 have a strong co-relation to its structural density, phase transformation and presence of Bi2Fe4O9 phase. These parameters are strongly dependent on the frequency, and its high values are obtained at low frequency because of the space charge polarization effect. The smaller values of impedance phase angles of BiFeO3, Bi0.90Ho0.10FeO3 and BiFe0.90Ho0.10O3 compounds compared to the anticipated $90^\circ$ 90 ∘ for an ideal capacitor show that these BFO-based compounds possess non-ideal capacitive/pseudocapacitive behavior. [ABSTRACT FROM AUTHOR]

A long‐standing issue about the correct identification of an important starting reagent, iron(III) hexafluoroacetylacetonate, Fe(hfac)3 (1), has been resolved. The tris‐chelated mononuclear complex was found to crystallize in two polymorph modifications which can be assigned as the low‐temperature (1‐L) monoclinic P21/n and the high‐temperature (1‐H) trigonal P. Low‐temperature polymorph 1‐L was found to transform to 1‐H upon sublimation at 44 °C. Two modifications are clearly distinguished by powder X‐ray diffraction (PXRD), single‐crystal X‐ray diffraction, differential scanning calorimetry (DSC), and melting‐point measurements. On the other hand, the two forms share similar characteristics in direct analysis in real‐time mass spectrometry (DART‐MS), attenuated total reflection (ATR) spectroscopy, and some physical properties, such as color, volatility, sensitivity, and solubility. Analysis of the literature and some of our preliminary data strongly suggest that the appearance of two polymorph modifications for trivalent metal (both transition and main group) hexafluoroacetylacetonates is a common case for several largely used complexes not yet accounted for in the crystallographic databases. [ABSTRACT FROM AUTHOR]

Molecular dynamics study of the influence of phase distribution on the response of two-phase nanocrystalline Fe95Ni05 samples with a gradient grained structure under shock loading was carried out. It was shown that the propagation of a shock wave causes direct and reverse FCC-BCC-FCC phase transformations in grains with the FCC structure, BCC-FCC/HCP phase transformations in lamellas with the BCC structure, as well as the nucleation of the HCP phase. The shock wave and the wave reflected from the rear surface initiated transformation of a significant part of the sample into the HCP phase. Shock wave propagation in the sample caused the appearance of two maxima on the curve of the time dependence of the HCP phase volume fraction. Time changes in the HCP phase fraction correlated with changes in the fraction of atoms belonging to intrinsic stacking faults and the dislocation density in the FCC phase. A large volume fraction of the intrinsic stacking faults, a higher dislocation density, and a lower volume fraction of the HCP phase were observed in the case of the sample with BCC lamellas only in one layer of grains compared to the sample with BCC lamellas in all grains under shock loading. [ABSTRACT FROM AUTHOR]

Phase transformations play a key role in numerous coupled natural processes, and they are important for many industrial applications. However, the kinetics of phase transformations in coupled chemo-mechanical systems undergoing large mechanical deformations still needs to be better quantified. Here, we study the phase transformation kinetics of a two-phase binary mixture using the diffuse interface approach. We couple a Cahn–Hilliard type model with a mechanical model for a compressible viscous flow. The bulk compressibility is a nonlinear function of the pressure, and the shear viscosity is a nonlinear function of the concentration. The mechanical coupling is achieved by employing a pressure-dependent mechanical mixing term in the equation for the Gibbs energy. We derive a dimensionless system of equations which we solve numerically with a pseudo-transient method using conservative finite differences for discretization. We perform numerical simulations in 1D and 2D model setups considering far-field simple shear and pure shear. For a chemo-mechanically coupled system, we show that the velocity of the phase boundary is a linear function of the degree of metastability and, hence, confirm the hypothesis of "normal growth." A stronger mechanical coupling and a larger volumetric effect of the chemical reaction result in lower phase boundary velocities. The 2D results show a significant impact of the mechanical coupling and the far-field deformation on the orientation and kinetics of the phase transformations. Under far-field simple shear and pure shear in 2D, the phase transformations generate string-like patterns. The orientation of these patterns is controlled by the applied far-field deformation and orientations differ by 45 degrees between simple shear and pure shear. [ABSTRACT FROM AUTHOR]