查看更多>>摘要：TC18 titanium alloy was subjected to hot rolling at 840 ℃,followed by annealing experiments at 830,860,and 890 ℃ for different time lengths.The effects of annealing temperature and time on phase transformation and static recrystallization(SRX)behavior,as well as the interaction between phase trans-formation and SRX,were studied.The results showed that at the low annealing temperature of 830 ℃,the microstructure underwent β → α phase transformation and α grain growth with the increase of annealing time,and the SRX of β phase proceeded through subgrain nucleation mechanism induced byα particles.At the middle annealing temperature(860 ℃),the α → β phase transformation occurred before the SRX of β phase,and the SRX of β phase was dominated by the grain boundary(GB)bulge mechanism.Meanwhile,the reduction of α phase content accelerated the SRX rate and grain growth.As the annealing temperature(890 ℃)exceeded the β transus temperature,the α phase completely trans-formed to the β phase,and the SRX of the β phase proceeded with a very fast grain growth rate.In addition,the interaction between phase transformation and SRX affected the distribution of α particles.The large-sized α particles(830 ℃)were located at the triple GB junction and hindered the SRX β grain growth,while smaller α particles(860 ℃)were bypassed by β GB and dispersed within the SRX β grains.
查看更多>>摘要：This study investigated the impact of surface degradation caused by oxygen(O)and nitrogen(N)ele-ments in the environmental atmosphere on the service failure of nearly lamellar TNM alloy.The results show that oxidation-induced phase transformations at the surface and subsurface regions strongly af-fect the alloy's tensile properties at high temperatures.The precipitation of Al2O3,which disrupts the integrity of the Ti2AlN layer,has a weaker deformation resistance capacity compared to the Z-phase.Un-der stress conditions,numerous dislocations concentrate at the Al2O3 phase,causing Al2O3 particles to easily detach and initiating crack nucleation at the Z-phase/Al2O3 interface.This is the origin of oxidation failure.Cracks nucleate at the Al2O3 detachment region,propagate,and connect with surface microcracks induced by the rough and loose outer oxide layer structure.This leads to the rapid propagation of cracks into the subsurface.The consumption of β-stabilizing elements at the surface,along with the internal dif-fusion of O and N elements into the subsurface region,results in the formation of the hard brittle Z-phase at the subsurface lamellar structure and a transition from β0 to α2 at the lamellar colony boundaries.The precipitation of α2 and Z-phase also accelerates crack propagation.In summary,the failure mode shifts from toughness fracture to brittle fracture.
查看更多>>摘要：The photoreduction of CO2 using solar energy to produce energy-efficient fuels is a sustainable technol-ogy that addresses energy needs while reducing carbon emissions.However,synthesizing efficient and robust photocatalysts for this process is challenging.This study introduces a viable approach for highly selective CO2 photoreduction to CH4 production by integrating defect-enriched BiOIO3(DEBI)with a Ti3C2(TC)MXene co-catalyst,forming an efficient 2D/2D Schottky-type heterostructure.The DEBI,enhanced with precise defect engineering,showed improved light absorption and charge separation efficiency.In tandem,the TC MXene co-catalyst facilitated rapid electron transfer and significantly minimized charge recombination.Consequently,the DEBI/TC-2 heterostructure,with an optimal 2 wt％TC MXene loading,achieved a CH4 yield of 52.8 μmol h-1 g-1,representing a remarkable 20.5-and 6.3-fold increase over pristine BiOIO3 and DEBI,respectively.The Schottky-type 2D/2D heterostructure also demonstrated an impressive apparent quantum yield of 0.72％,99％CH4 selectivity over H2 generation,and remarkable stability across multiple cycles.This study underscores the synergistic advantages of defect engineering and MXene co-catalyst integration in a single system,proposing a novel direction for designing highly efficient photocatalysts for solar-driven CO2 reduction in energy-efficient fuel production.
查看更多>>摘要：Among the many strategies for CO2 resource utilization,the synthetic technology of cyclic carbonates with 100％atom economy through CO2and epoxide is one of the most industrially viable routes,but its efficiency has been severely hampered by the lack of highly active catalytic sites.Moreover,due to the intrinsic thermodynamic stability and kinetic inertia of CO2 and the higher energy barrier of the ring-opening reaction of epoxides,the heterogeneous catalytic conversion of CO2 highly depends on harsh operating conditions,high temperatures and pressures,and the incorporation of cocatalysts.The devel-opment of efficient heterogeneous catalysts for CO2 conversion under cocatalyst-free and mild conditions has always been a challenge.Herein,we have proposed a synergetic strategy of facet and vacancy engi-neering for the construction of highly efficient heterogeneous catalyst BiO1-xBr1-y-(010)for CO2 cycload-dition,where introducing the OVs-BrVs pairs into typical(010)facets BiOBr with simultaneous surface Lewis acid sites Bi3+and nucleophilic sites Br-.By combining theoretical calculations and a series of systematic experiments,such as CO2 temperature-programmed desorption,electron paramagnetic res-onance and fluorescence probe analysis experiments,the introduced OVs-BrVs pair can not only form Bi3+-Bi(3-x)+dual active sites on the surface,which activate PO and CO2 respectively to reduce the energy barrier of CO2 insertion,but also activate Br-near BrVs to enhance their nucleophilic attacking ability and reduce the energy barrier of epoxides ring-opening.As a result,the BiOi-xBr1-y-(010)with abundant surface OVs-BrVs pairs showed a high cyclic carbonates conversion of 99％with 100％selectivity un-der cocatalyst-free and mild conditions,far surpassing most heterogeneous catalytic systems.This work provides a completely new strategy to construct high-performance heterogeneous CO2 cycloaddition cata-lysts through a simple facet and vacancy engineering strategy to overcome the harsh operating conditions limitation and the use of cocatalysts.
查看更多>>摘要：This study provides a potentially viable approach to manipulate the precipitation of primary carbides in molten steel by modifying the diffusion coefficient of carbon.The solidification process of a Fe-C alloy is simulated using the multi-phase-field method,and we focus on the impact of diffusion coefficient of carbon on the solute segregation and cementite precipitation.Two benefits have been revealed as the ratio of the diffusivities of carbon in solid to that in liquid is increased.A potential advantage is the re-duction in the volume fraction of the residual liquid enriched with carbon during the late solidification.Furthermore,the magnitude of the chemical driving force for the phase transition of cementite precip-itation will be lower.The combined influence of both factors results in an exponential decrease in the volume fraction of cementite formed at the end of solidification.
查看更多>>摘要：To provide insight into the effect of grain size on the precipitation behavior of γ"strengthening super-alloy Inconel 718,a gradient nanostructure with a large grain size span(from 9 nm to tens of microns)along the depth direction was achieved by mean of surface mechanical grinding treatment,followed by annealing upon 700-1000 ℃ for 1 h.The results reveal significant differences in the type and size of precipitates in samples with different grain sizes.No y"precipitate was detected inside the grains as the grain size was refined down to 40 nm(NG-40)and 9 nm(NG-9).For δ phase,a significantly accelerated precipitation along grain boundary was observed in NG-40 upon 700 ℃ annealing.Interestingly,with the grain size drops to 9 nm,the precipitation of δ was suppressed,with some nanosized MC carbides appearing upon annealing.The grain size effect of precipitation behavior endows NG-9 an ultra-high RT-hardness(5.2 GPa)after 1000 ℃ thermal exposure and an ultra-high hot-hardness(3.2 GPa)at 800 ℃.
查看更多>>摘要：Superior photo-mineralization of pollutants,outstanding charge separation efficiency and exceptional photostability of catalysts constitute three pivotal factors for the effective photodegradation of organic pollutants.In this study,a dual S-scheme In2O3/Pedot/ln2S3(IO/Pedot/IS),inspired by natural photosyn-thesis,was successfully synthesized for the degradation of lignin and antibiotics.The resulting exceptional semiconductor contact creates a dual-interface electric field on Pedot,facilitating multi-channel charge transport and enhancing charge separation efficiency.The establishment of the dual S-scheme hetero-junction raised the reduction-oxidation potential of the type-Ⅱ In2O3/In2S3.When subjected to 5 W LED irradiation for 60 min,IO/Pedot-2/IS demonstrated a remarkable mineralization rate of 85.8％for sodium lignosulfonate(SL),surpassing the 53.7％mineralization rate achieved by IO/IS.Furthermore,the degra-dation efficiency for tetracycline(TC)and ciprofloxacin(CIP)reached 91％and 88％,respectively.Crucially,the hole(h+)conductivity of Pedot efficiently alleviated the photocorrosion of sulfide,ensuring robust cyclic stability.Experimental simulations of natural photocatalysis showcased the exceptional versatility and applicability of IO/Pedot/IS.In-depth analysis led to the proposal of a potential photodegradation pathway for lignin,based on the intermediates detected through liquid chromatography-mass spectrom-etry(LC-MS).Overall,this study presents an effective strategy for the efficient photocatalytic treatment of organic pollutants.
Faiza BibiIrfan Ali SoomroAbdul HananMuhammad Nazim Lakhan...
82-118页
查看更多>>摘要：MXene-based 2D heterostructures have emerged as a highly promising area of research in the field of energy storage and conversion,owing to their exceptional properties and versatility.This comprehensive review aims to highlight the recent advancements and challenges associated with tailoring MXene-based heterostructures.The review focuses on the progress made in the past decade regarding 2D/2D MXene-based heterostructures for energy storage/conversion.The influence of interfacial interactions,electronic conductivity,ion diffusion pathways,and surface chemistry on the performance of these heterostructures in supercapacitors,batteries,and water-splitting reactions have been critically examined.By considering these factors,researchers gain insights into the design principles and optimization strategies for MXene-based heterostructures.By understanding the progress made and the existing challenges,researchers can further explore the vast potential of MXene heterostructures and contribute to the development of next-generation energy storage and conversion technologies.
查看更多>>摘要：In this work,the influence of the hot-extrusion method on the hydrogen storage kinetics of Mg-Ni-Y alloy was investigated.It was shown that the extruded Mg91.47Ni6.97Y1.56 alloy exhibits improved hydriding and dehydriding(H/D)kinetics,with a capacity of 3.5 wt.％H2 absorption within 60 s and 5.4 wt.％H2 des-orption within 5 min at 573 K.The dehydrogenation activation energy of extruded alloy is 71.4 kJ mol-1,smaller than that of as-cast alloy(140.5 kJ mol1).The enhancement of H/D kinetics is attributed to the microstructural refinement and increased grain/phase boundaries introduced by hot extrusion,as well as the catalytic effects from the in-situ generated and grain-refined Mg2Ni and YH2 particles during the H/D process.Furthermore,the dehydrogenated rate-determining step transforms from hydrogen diffusion in the hydride(as-cast alloy)to the surface penetration of hydrogen atoms(extruded alloy).These findings provide crucial insights for the design of Mg-based hydrogen storage alloys in the future.
查看更多>>摘要：Fog collection materials have been intensively investigated and can potentially be used to alleviate fresh-water shortages.However,developing highly efficient fog collection materials remains challenging.Requi-site improvements in fog collection technology are the ultrafast transportation of captured water and the effective regeneration of fresh regions on the surfaces of fog collection materials.Herein,a novel Janus mesh membrane(JMM)with an alternating hydrophobic-superhydrophilic-patterned hydrophobic surface and asymmetric wettability interface is prepared by a selective liquid-phase surface oxidation strategy.The unique structure and high-contrast wettability of the JMM enable ultrafast directional transportation of tiny water droplets(＜0.1 μL),thereby achieving an excellent water collection efficiency of 15.28 g h-1 cm-2,which is much higher than those of conventional Janus membranes.The JMM functioned as a versatile fog collector and maintained continuous fog collection regardless of the fog flow direction.This study offers a novel approach for preparing innovative fog collection materials and establishes a founda-tion for developing advanced fog collection systems suitable for diverse applications.
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