Mechanical wet-milling and subsequent consolidation of ultra-fine Al_2O_3-(ZrO_2+3%Y_2O_3) bioceramics by using high-frequency induction heat sintering

Alumina/zirconia composites were synthesized by wet-milling technique and rapid consolidation with high frequency induction heat sintering(HFIHS). The starting materials were a mixture of alumina micro-powder (80%, volume fraction) and 3YSZ nano-powders (20%). The mixtures were optimized for good sintering behaviors and mechanical properties. Nano-crystalline grains are obtained after 24 h milling. The nano-structured powder compacts are then processed to full density at different temperatures by HFIHS. Effects of temperature on the mechanical and microstructure properties were studied. Al2O3-3YSZ composites with higher mechanical properties and small grain size are successfully developed at relatively low temperatures through this technique.

Growth of BaTiO_3-Ag hybrid composite films at room temperature by aerosol deposition

Barium titanate (BaTiO3) and silver (Ag) composite film with high dielectric constant was grown at room temperature by an aerosol deposition method.The dielectric constant increases by 0.5 times after adding Ag to the BaTiO3 matrix,compared with pure BaTiO3.The high dielectric constant can be attributed to the percolation effect of Ag inclusions in the BaTiO3 matrix.The Ag was present in the form of discrete layer in the BaTiO3 film.The dielectric properties of BaTiO3 Ag were discussed in detail taking into account the changes in microstructures.

Tensile creep and corrosion properties of Mg-2%Ca based cast alloys

The relative effect of Zn addition to Mg-2%Ca based alloy on the creep and corrosion characteristics was compared with Al addition. The creep resistance of Mg-2%Ca based alloy at 175 ℃was improved by Zn addition more significantly than by Al addition. However, the Al addition showed more effective in enhancing corrosion resistance. Since the solidification range for Zn-added alloy was considerably wide, the cautious casting design may be necessary to produce high-quality castings.

Solar‑Driven Sustainability:Ⅲ–ⅤSemiconductor for Green Energy Production Technologies

Long-term societal prosperity depends on addressing the world’s energy and environmental problems,and photocatalysis has emerged as a viable remedy.Improving the efficiency of photocatalytic processes is fundamentally achieved by optimizing the effective utilization of solar energy and enhancing the efficient separation of photogenerated charges.It has been demonstrated that the fabrication ofⅢ–Ⅴsemiconductor-based photocatalysts is effective in increasing solar light absorption,long-term stability,large-scale production and promoting charge transfer.This focused review explores on the current developments inⅢ–Ⅴsemiconductor materials for solar-powered photocatalytic systems.The review explores on various subjects,including the advancement ofⅢ–Ⅴsemiconductors,photocatalytic mechanisms,and their uses in H2 conversion,CO_(2)reduction,environmental remediation,and photocatalytic oxidation and reduction reactions.In order to design heterostructures,the review delves into basic concepts including solar light absorption and effective charge separation.It also highlights significant advancements in green energy systems for water splitting,emphasizing the significance of establishing eco-friendly systems for CO_(2)reduction and hydrogen production.The main purpose is to produce hydrogen through sustainable and ecologically friendly energy conversion.The review intends to foster the development of greener and more sustainable energy source by encouraging researchers and developers to focus on practical applications and advancements in solar-powered photocatalysis.

Two-stage dynamic recrystallization and texture evolution in Al-7Mg alloy during hot torsion

Hot torsion tests were performed on the Al-7Mg alloy at the temperature ranging from 300 to 500℃ and strain rates between 0.05 and 5 s^(-1) to explore the progressive dynamic recrystallization(DRX)and texture behaviors.The DRX behavior of the alloy manifested two distinct stages:Stage 1 at strain of≤2 and Stage 2 at strains of≥2.In Stage 1,there was a slight increase in the DRXed grain fraction(X_(DRX))with predominance of discontinuous DRX(DDRX),followed by a modest change in X_(DRX) until the transition to Stage 2.Stage 2 was marked by an accelerated rate of DRX,culminating in a substantial final X_(DRX) of~0.9.Electron backscattered diffraction(EBSD)analysis on a sample in Stage 2 revealed that continuous DRX(CDRX)predominantly occurred within the(121)[001]grains,whereas the(111)[110]grains underwent a geometric DRX(GDRX)evolution without a noticeable sub-grain structure.Furthermore,a modified Avrami’s DRX kinetics model was utilized to predict the microstructural refinement in the Al-7Mg alloy during the DRX evolution.Although this kinetics model did not accurately capture the DDRX behavior in Stage 1,it effectively simulated the DRX rate in Stage 2.The texture index was employed to assess the evolution of the texture isotropy during hot-torsion test,demonstrating significant improvement(>75%)in texture randomness before the commencement of Stage 2.This initial texture evolution is attributed to the rotation of parent grains and the substructure evolution,rather than to an increase in X_(DRX).

Light-Material Interactions Using Laser and Flash Sources for Energy Conversion and Storage Applications

This review provides a comprehensive overview of the progress in light-material interactions(LMIs),focusing on lasers and flash lights for energy conversion and storage applications.We discuss intricate LMI parameters such as light sources,interaction time,and fluence to elucidate their importance in material processing.In addition,this study covers various light-induced photothermal and photochemical processes ranging from melting,crystallization,and ablation to doping and synthesis,which are essential for developing energy materials and devices.Finally,we present extensive energy conversion and storage applications demonstrated by LMI technologies,including energy harvesters,sensors,capacitors,and batteries.Despite the several challenges associated with LMIs,such as complex mechanisms,and high-degrees of freedom,we believe that substantial contributions and potential for the commercialization of future energy systems can be achieved by advancing optical technologies through comprehensive academic research and multidisciplinary collaborations.

低温烧结原位合成微米级Al_2O_3颗粒强化Al基复合材料

以Al-10wt%SiO2粉末为研究体系,对比机械混合与球磨的粉末,研究了球磨粉末的相组成和微结构,用差热分析的方法确定了两种粉末体系中的置换反应发生的温度,以此为据,优化了烧结两种粉末压坯的工艺。结果表明,4h球磨的粉末颗粒明显细化,部分SiO2颗粒嵌入Al基体,形成反应扩散耦Al/SiO2;混合粉末中置换反应不能发生,球磨粉末中置换反应的温度区间为560-680℃;球磨粉末的压坯在640℃烧结2h,可形成组织均匀的微米级Al2O3颗粒强化Al基复合材料。

Interface properties and phase formation between surface coated SKD61 and aluminum alloys

The intermediate phase formation and surface protection effects between SKD61 die mold alloys and aluminum alloys were investigated during a simulated die-casting process.The surface coatings of SKD61 alloy were carried out via Si pack cementation coatings at 900 ℃ for 10 h and the ε-FeSi phase formed.When the coated SKD61 alloy was dipped in the liquid aluminum alloy(ALDC12),the surface coated SKD61 alloys showed better surface properties compared with uncoated SKD61 alloys,i.e.,the intermediate phases(FeSiAl compound) were not produced for the coated SKD61 alloy.The coating layer of ε-FeSi served as a diffusion barrier for the formation of FeSiAl compounds.

喷墨印刷／软光刻技术结合气相聚合法制备聚3，4-乙撑二氧噻吩图像

采用气相聚合,以咪唑衍生物为辅助料可以成功制备高导电透明的聚3,4-乙撑二氧噻吩(PEDOT)薄膜。带有1～2个烷基官能团的咪唑衍生物的加入可以显著提高PEDOT的电导率。为了研制一种易于实现的PEDOT成像法,本文采用了喷墨印刷或软光刻技术结合气相聚合法,并以带取代基的对甲苯磺酸铁为氧化剂,3,4-乙撑二氧噻吩为聚合单体来制备PEDOT图像。这种新型方法的实现将为制得本征导电高分子材料图像提供一个高效便捷的方法。

Functionally Graded Ti-50.5Ni Alloy

Transformation behavior and shape memory characteristics of a temperature gradient annealing(TGA)treated Ti-50.5Ni(at%)alloy have been investigated by means of differential scanning calorimetry(DSC)and thermal cycling tests under constant load.By annealing the specimen under the temperature gradient from 823 K to 658 K after solution treatment,the B19' martensitic transformation start temperature changed by 60 K along the length of sample(150mm).Temperature dependence of transformation elongation(dε/dT)of the TGA treated wire was found to be 0.16 %/K.By annealing the specimen under the temperature gradient from 823 K to 658 K after 47 % cold working without solution treatment,the B19' martensitic transformation start temperature changed by 61K along the length of sample(150mm).Temperature dependence of transformation elongation(dε/dT)of the TGA treated wire was found to be 0.04 %/K.The large decrease in dε/dT by cold working effect suggested that an introduction of dislocation was more effective than precipitates for lowering dε/dT.

Strengthening mechanisms analysis and tailoring of bimodal grain structures for enhanced strength in CoCrFeMnNi high-entropy alloys

The CoCrFeMnNi high-entropy alloys(HEAs)with a(face-centered cubic) FCC structure has garnered considerable attention for its exceptional ductility and strain hardening ability.However,its yield strength is insufficient for structural applications.In this study,strengthening mechanisms in these HEAs were investigated to gain insight into the mechanical properties according to alloy powder size.Moreover,we present a novel approach to achieve both high strength and high ductility through the creation of a bimodal structure consisting of both coarse and fine grains via gas atomization and spark plasma sintering processes.A bimodally structured HEA prepared with a mass ratio of 2:8 between coarse particles(75-106 μm) and fine particles(≤25 μm)yielded optimal results,with a strength of 491.95 MPa and elongation of 19.64%.This strength value represents an~41% increase compared with the sample that displayed a fine single microstructure(347.08 MPa for yield strength).The strength enhancement was attributed to the prevention of plastic deformation initiation from the fine particles during deformation.This innovative approach to the creation of HEAs with bimodal structures shows promise for various applications,such as structural components that require a combination of high strength and high ductility.

Understanding microstructure and mechanical properties of(AlTa(0.76))xCoCrFeNi(2.1) eutectic high entropy alloys via thermo-physical parameters

(AlTa(0.76))xCoCrFeNi(2.1)(x values in molar ratio,x=0.1,0.3,0.5,0.7,1.0,and 1.5) alloys were designed to investigate the microstructure and mechanical properties of the eutectic high entropy alloys(EHEAs)consisting of FCC,B2,and Laves phases.Depending on the compositional variatio,clear microstructural variation was observed,as follows:(1) Group 1:FCC dendrite+Laves interdendrite(x=0.1),(2) Group 2:FCC dendrite+fine-eutectic structure consisting of FCC and Laves phases(x=0.3,0.5 and 0.7),(3) Group 3:B2 dendrite+bimodal eutectic structure [FCC/B2+Laves](x=1.0),(4) Group 4:Laves dendrite+eutectic structure consisting of B2 and Laves phases(x=1.5).As the fraction of Laves or B2 phases increases,yield stress increases from 293 to 2336 MPa,while the plastic strain decreases from 50 % to 2%.Thermo-physical parameters,such as mixing entropy(△S(mix)),mixing enthalpy(△H(mix)),valence electron concentration(VEC),and atomic size difference(δr),were calculated to understand the microstructural variation.Two criteria(δr-VEC and δr-△H(mix)) were utilized to elucidate the formation of the eutectic structures in the present EHEAs,revealing the usefulness of the thermo-physical parameters in the development of EHEAs.

Substrate Temperature Dependent Properties of Cu Doped NiO Films Deposited by DC Reactive Magnetron Sputtering

The NiO-Cu composite films were deposited on a glass substrate at various substrate temperatures by DC reactive magnetron sputtering technique. The effect of substrate temperature on the structural, optical, morphological and electrical properties of the films was mainly investigated. X-ray diffraction studies revealed that when the substrate temperature increased to above 200 ℃, the preferred orientation tended to move to another preferred site from （220） to （111） and had a band gap values increased with increasing substrate observed that the grain size and root mean square stable cubic structure. The optical transmittance and temperature. From the morphological studies, it was roughness were increased with increasing substrate temperature. The electrical resistivity of the film decreased to 0.017 Ωcm at high substrate temperature of 400 ℃.

Prediction of Nitrogen Diffusivity in α-ferrite Based on Thermodynamics

A thermodynamic based equation to predict the diffusivity of nitrogen in α-ferrite was investigated in consideration of the equilibrium nitrogen concentration. The temperature-dependent jump distance calculated from the lattice parameter of ferrite was used to derive the frequency factor as a function of temperature. The calculation accuracy for nitrogen diffusivity using the proposed thermodynamic based equation was improved by comparing the calculation results using previous empirical equations based on Arrhenius type relationship with measured diffusivity of nitrogen for α-ferrite at different temperatures.

Flexible mica films coated by magnetron sputtered insulating layers for high-temperature capacitive energy storage

High-temperature energy storage performance of dielectric capacitors is cru-cial for the next generation of power electronic devices.However,conduction losses rise sharply at elevated temperature,limiting the application of energy storage capacitors.Here,the mica films magnetron sputtered by different insulating layers are specifically investigated,which exhibit the excellent high-temperature energy storage performance.The experimental results revealed that the PbZrO3/Al2O3/PbZrO3(PZO/AO/PZO)interface insulating layers can effec-tively reduce the high-temperature leakage current and conduction loss of the composite films.Consequently,the ultrahigh energy storage density(Wrec)and charge‒discharge efficiency(η)can be achieved simultaneously in the flexi-ble mica-based composite films.Especially,PZO/AO/PZO/mica/PZO/AO/PZO(PAPMPAP)films possess excellent Wrec of 27.5 J/cm3 andηof 87.8%at 200◦C,which are significantly better than currently reported high-temperature capaci-tive energy storage dielectric materials.Together with outstanding power density and electrical cycling stability,the flexible films in this work have great appli-cation potential in high-temperature energy storage capacitors.Moreover,the magnetron sputtering technology can deposit large-area nanoscale insulating layers on the surface of capacitor films,which can provide technical support for the industrial production of capacitors.

“One stone,two birds”solvent system to fabricate microcrystalline cellulose–Ti_(3)C_(2)T_(x)nanocomposite film as a flexible dielectric and thermally conductive material

A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was developed.The MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control drying.The MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial polarization.Thus,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered structure.Additionally,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and flexibility.Furthermore,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of MXene.Moreover,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous systems.With the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.

Ultra-flexible semitransparent organic photovoltaics

Ultra-flexible organic photovoltaics(OPVs)are promising candidates for next-generation power sources owing to their low weight,transparency,and flexibility.However,obtaining ultra-flexibility under extreme repetitive mechanical stress while maintaining optical transparency remains challenging because of the intrinsic brittleness of transparent electrodes.Here,we introduce straindurable ultra-flexible semitransparent OPVs with a thickness below 2μm.The conformal surface coverage of nanoscale thin metal electrodes(<10 nm)is achieved,resulting in extremely low flexural rigidity and high strain durability.In-depth optical and electrical analyses on ultrathin metal electrodes showed that the devices maintain over 73%of their initial efficiency after 1000 cycles of repetitive compression and release at 66%compressive strain,and the average visible light transmittances remain higher than 30%.To our knowledge,this is the first systematical study on mechanical behaviors of strain-durable ultra-flexible ST-OPVs through precise adjustment of each ultrathin electrode thickness toward the emergence of next-generation flexible power sources.