Invar steels possess excellent thermal expansion properties,making them suitable as materials for manufacturing precision instruments.However,conventional invar steels lack sufficient strength for engineering applicat...Invar steels possess excellent thermal expansion properties,making them suitable as materials for manufacturing precision instruments.However,conventional invar steels lack sufficient strength for engineering applications,and various strengthening methods are urgently needed to enhance their strength.In this work,the possibility of enhancing the strength and maintaining low coefficient of thermal expansion(CTE)of the steel through mechanical heat treatment and the introduction of vanadium carbonitride is demonstrated.V-N microalloying and various heat treatment processes enable invar steel to enhance its strength while maintaining low thermal expansion properties.The strength of low-nitrogen addition invar steel measured 593 MPa during direct aging,representing a 44.6% increase compared to invar steel.After undergoing cold-deformation aging,the strength of low-nitrogen invar steel increased to 790 MPa,indicating a substantial improvement in strength relative to the direct aging condition.Notably,the coefficient of thermal expansion remained at 0.98×10^(-6)℃^(-1).By further increasing N content to introduce more vanadium carbonitride,the strength of high-nitrogen invar steel reached 927 MPa under cold-deformation process while maintaining a low CTE value of 1.02×10^(-6)℃^(-1).This achieved an extraordinary balance of high strength and low CTE,which is due to a well combination of various strengthening mechanisms,especially the Orowan strengthening where dislocations continuously bypass vanadium carbonitride to achieve the strengthening effect.The resulting findings are important for future preparation of excellent properties invar steel in industrial applications.展开更多
Based on mass balance and solubility product equations, a thermodynamic model enabling the calcula- tion of equilibrium carbonitride composition and relative amounts as a function of steel composition and tem- peratur...Based on mass balance and solubility product equations, a thermodynamic model enabling the calcula- tion of equilibrium carbonitride composition and relative amounts as a function of steel composition and tem- perature was developed, which provides a method to es- timate the carbonitride complete dissolution temperature for different steel compositions. Actual carbonitride pre- cipitation behavior was further verified in Ti-V-C-N microalloyed steel system. The model suggests that for higher IV] and [Ti] dissolved in steels, it is available to decrease the addition of C and N during alloy composi- tion design. The resultant longer fatigue life of the modified steel could be attributed to the more [V] and [Ti] dissolved in the matrix, inducing finer dispersion of carbonitrides. Therefore, this model is proved to be effective in determining better chemical composition for high-performance steels, leading to possible reductions in the cost of production and improvements in the combined mechanical properties of the steels.展开更多
In this work, the growth kinetics of MX （M - metal, X - C/N） nanoprecipitates in type 347H austenitic steel was systematically studied. To investigate the coarsening behavior and the growth mechanism of MX carbonitr...In this work, the growth kinetics of MX （M - metal, X - C/N） nanoprecipitates in type 347H austenitic steel was systematically studied. To investigate the coarsening behavior and the growth mechanism of MX carbonitrides during long-term aging, experiments were performed at 700, 800, 850, and 900℃ for different periods （1, 24, 70, and 100 h）. The precipitation behavior of carbonitrides in specimens subjected to various aging conditions was explored using carbon replicas and transmission electron microscopy （TEM） observations. The corresponding sizes ofMX carbonitrides were measured. The results demonstrates that MX carbonitrides precipitate in type 347H austenitic steel as Nb（C,N）. The coarsening rate constant is time-independent; however, an increase in aging temperature results in an increase in coarsening rate of Nb（C,N）. The coarsening process was analyzed according to the calculated diffusion activation energy of Nb（C,N）. When the aging temperature was 800-900℃, the mean activation energy was 294 kJ·mol -1, and the coarsening behavior was controlled primarily by the diffusion of Nb atoms.展开更多
According to the misfitting dislocation theory,a method of theoretical calculation was devel- oped for the specific energy of the semicoherent interface between microalloy carbonitrides and austenite matrix.The calcul...According to the misfitting dislocation theory,a method of theoretical calculation was devel- oped for the specific energy of the semicoherent interface between microalloy carbonitrides and austenite matrix.The calculating formulae were derived and the results were satisfactorily applied on the research works.展开更多
The strain-induced isothermal precipitation and the law of coarsening of Nb,V and Ti carbonitrides in Nb-steel.V-steel.Nb-V steel and Ti-V-Nb steel have been investigated systematically by means of STEM,EDAX,a new ext...The strain-induced isothermal precipitation and the law of coarsening of Nb,V and Ti carbonitrides in Nb-steel.V-steel.Nb-V steel and Ti-V-Nb steel have been investigated systematically by means of STEM,EDAX,a new extraction replica technique and the quanti- tative phase analyses method.展开更多
The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence thethermoplasticity,thereby affecting the quality of the slab.In this work,a prediction model...The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence thethermoplasticity,thereby affecting the quality of the slab.In this work,a prediction model for two-stage austenite growth under varyingcooling rates was established by incorporating the effect of second-phase pinning and high-temperature ferrite-austenite phase transform-ation and growth theory.The results indicate that with 0.02wt%Ti,the high-temperature ferrite growth exhibits typical parabolic growthcharacteristics.When the Ti content increases to 0.04wt%,the high-temperature ferrite grain boundary migration rate significantly slowsduring the initial solidification stage.The predicted austenite grain sizes for 0.02wt%Ti microalloyed steel at the center,quarter,and sur-face of the slab are 5592,3529,and 1524μm,respectively.For 0.04wt%Ti microalloyed steel,the austenite grain sizes are 4074,2942,and 1179μm at the same positions.The average error is within 5%.As the Ti content increases from 0.02wt% to 0.04wt%,the austenitegrain refinement at the center is most significant,with an average grain size reduction of 27.14%.展开更多
Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corre...Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corrected from 1 to 2.The correct author affiliation has been provided in this Correction and the original article[1]has been corrected.展开更多
High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting...High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting.An equivalent austenite diameter was proposed,taking into account the weakening effects of proeutectoid ferrite films and Ti carbonitride precipitation.Based on this,a hot ductility prediction model for the slab was established to investigated hot ductility.The results show that as Ti content increases,the hot ductility of Ti microalloy steel initially increases and then decreases.At low Ti content,the pinning effect of Ti carbonitrides increases with the increase in Ti content,which inhibits grain coarsening for improving hot ductility.As Ti content increases,the size of carbonitrides grows,weakening the pinning effect and leading to austenite grain coarsening.Simultaneously,the formation of Ti carbonitrides inhibits proeutectoid ferrite film formation,leading to a reduction in its thickness.These combined factors reduce the hot ductility of the continuous casting steel.According to the hot ductility prediction model,in order of severity,the factors affecting hot ductility are:proeutectoid ferrite film,chain-like nanoscale Ti carbonitrides,austenite grain size,and dispersed nanoscale Ti carbonitrides.An accuracy error of less than 10%is shown by the model.展开更多
Hafnium carbonitride(HfC_(x)N_(1-x))ceramics have drawn considerable interest due to their exceptional me-chanical and thermophysical properties.Herein,we report a novel single-source precursor with Hf-N bonds as the ...Hafnium carbonitride(HfC_(x)N_(1-x))ceramics have drawn considerable interest due to their exceptional me-chanical and thermophysical properties.Herein,we report a novel single-source precursor with Hf-N bonds as the main chain and fabricate HfC_(x)N_(1-x)ceramics after pyrolysis of the precursor.The synthesis,ceramic conversion,and microstructural evolution of the single-source precursor as well as the derived HfC_(x)N_(1-x)ceramics treated under various atmospheres were investigated.The results indicate that in an argon atmosphere,the nitrogen content within HfC_(x)N_(1-x)decreases with rising temperature.While under a nitrogen atmosphere,the high concentration of N_(2)facilitates the rapid conversion of HfO2 to Hf7O8N4,which subsequently promotes the transformation of the HfC_(x)N_(1-x)solid solution ceramics.During this process,there is also an inhibitory effect of N_(2)on the tendency of HfN into HfC.Moreover,the desired chemical composition of HfC_(x)N_(1-x)can be regulated by adjusting the N_(2)concentration in the heat treat-ment atmosphere.The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfC_(x)N_(1-x)ceramics.展开更多
The precipitation strengthening mechanism of microalloy carbonitrides (M(CN) phases) in ferrite is a basic research work on the precipitation strengthening behaviour of microalloy steels. Generally speaking, the preci...The precipitation strengthening mechanism of microalloy carbonitrides (M(CN) phases) in ferrite is a basic research work on the precipitation strengthening behaviour of microalloy steels. Generally speaking, the precipitation strengthening effect is regarded as the result展开更多
The morphology,size,quantity,and composition of complex oxide+carbonitride in H13 steel held at 1250℃for 5,10,and 15 h were determined.The results show that the ratio and number of complex carbonitrides with cores in...The morphology,size,quantity,and composition of complex oxide+carbonitride in H13 steel held at 1250℃for 5,10,and 15 h were determined.The results show that the ratio and number of complex carbonitrides with cores in H13 steel are gradually increased when holding at 1250℃compared with those in the original H13 steel,and the core size increases.There are one or more oxide cores in(Ti_(x),V_(1-x))(Cy,N_(1-y)),including xCaO·zAl_(2)O_(3),xCaO·yMgO·zAl_(2)O_(3),and CaO after holding at 1250℃,in addition to MgO·Al_(2)O_(3)and Al_(2)O_(3)in the original steel.The equilibrium temperature for(Ti_(x),V_(1-x))(Cy,N_(1-y))precipitation at the solidification front and decomposition in the solid state was theoretically analyzed,which was affected by the x value and the product of Ti and N contents in H13 steel.Meanwhile,the composition of(Ti_(x),V_(1-x))(Cy,N_(1-y))is influenced by the oxide cores.It is convinced that(Ti_(x),V_(1-x))(Cy,N_(1-y))with oxide cores has a higher stability,especially for oxides with a high Al_(2)O_(3)content.Heat treatment at high temperature facilitates a more reasonable analysis of oxide+carbonitride,and the generation mechanism of oxide+carbonitride was discussed.展开更多
Carbonitride MXenes,such as Ti_(3)CNT_(x),Ti_(2)C_(0.5)N_(0.5)T_(x),and Ti_(4)(C_(0.2)N_(0.8))_(3)T_(x),have attracted much interest in the large family of two-dimensional(2D)nanomaterials.Like their carbide MXene cou...Carbonitride MXenes,such as Ti_(3)CNT_(x),Ti_(2)C_(0.5)N_(0.5)T_(x),and Ti_(4)(C_(0.2)N_(0.8))_(3)T_(x),have attracted much interest in the large family of two-dimensional(2D)nanomaterials.Like their carbide MXene counterparts,the nanolayered structure and functional groups endow carbonitride MXenes with an attractive combination of physical and chemical properties.More interestingly,the replacement of C by N changes the lattice parameters and electron distribution of carbonitride MXenes due to the greater electronegativity of N as compared to C,thus resulting in significantly enhanced functional properties.This paper reviews the development of carbonitride MXenes,the preparation of 2D carbonitride MXenes,and the current understanding of the microstructure,electronic structure,and functional properties of carbonitride MXenes.In addition,applications,especially in energy storage,sensors,catalysts,electromagnetic wave shielding and absorption,fillers,and environmental and biomedical fields,are summarized.Finally,their current limitations and future opportunities are presented.展开更多
As a new type of two-dimensional material,MXene’s unique layered structure,outstanding electrical conductivity,low density,tunable surface chemistry,and solution processability make it receive extensive attention in ...As a new type of two-dimensional material,MXene’s unique layered structure,outstanding electrical conductivity,low density,tunable surface chemistry,and solution processability make it receive extensive attention in various fields,especially for the lightweight shielding mate rials since the report on electromagnetic interference(EMI) shielding of 2D Ti3 C2 Tx in 2016.In this review,the progress on the MXe nes material including their synthetic strategies,prope rties and EMI application is highlighted.First,the recent advance on the different synthesis methods and properties of MXene is summarized.According to their intrinsic characteristics,the application of MXene in EMI fields is then discussed.Finally,the challenges and perspective on the future development of MXene in low-cost preparation and practical application are proposed.展开更多
The characteristics and generation mechanism of（Ti,Nb,V）（C,N） precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of（Ti,Nb,V）（C,N） phases exist—a Ti-V-r...The characteristics and generation mechanism of（Ti,Nb,V）（C,N） precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of（Ti,Nb,V）（C,N） phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich（Ti,Nb,V）（C,N） precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2–5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of（Ti,Nb,V）（C,N） is concentrated. The average composition of the single Ti-V-rich phase is（Ti_（0.511）V_（0.356）Nb_（0.133））（CxNy）, whereas that for the single Nb-rich phase is（Ti_（0.061）V_（0.263）Nb_（0.676））（C_xN_y）. The calculation results based on the Scheil–Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.展开更多
Two martensitic stainless steels of 2Cr12Ni6 type hardened and tempered at 773 K have been studied:the first with 0.2%carbon content and the second with partial replacement of carbon by nitrogen(C0.1N0.1)in the first ...Two martensitic stainless steels of 2Cr12Ni6 type hardened and tempered at 773 K have been studied:the first with 0.2%carbon content and the second with partial replacement of carbon by nitrogen(C0.1N0.1)in the first steel.It is found that the partial substitution of carbon with nitrogen contributed to an increase in ductility and strength of the steel,presumably due to the formation of more dispersive carbonitrides.Meanwhile,the addition of nitrogen suppressed the precipitation of carbonitrides,so that the solid solution strengthening effect of C0.1N0.1 did not decrease significantly after tempering treatment.In addition,the partial replacement of carbon by nitrogen contributed to improved ability against pitting corrosion(PC)in chloride-containing medium(3.5%NaCl at 303 K).The higher resistance to PC of tempered nitrogen-containing steel is apparently due to the lower content of massive carbonitrides,especially the reduced aggregation at grain boundaries.This leads to a lower acidity and aggressiveness of the test solution near the sample surface due to the accumulation of NH4^(+) ammonium ions in it.As a result of nitrogen addition,exception for Cr_(23)C_(6) and VC,Cr_(2)N and(Cr,V)N type precipitates have also been found in C0.1N0.1 steel and this is consistent with the thermodynamic calculation results.In conclusion,substituting carbon by nitrogen in traditional martensitic stainless steel could realize the simultaneous improvement of multiple properties of martensitic stainless steels.This result provides a promising composition optimization route to develop novel martensitic stainless steels.展开更多
Double-hit compression tests were performed on StE460 steel containing microalloying elements niobium and vanadium over a range of temperatures and strain rates penment to hot rolling. The fractional softening was eva...Double-hit compression tests were performed on StE460 steel containing microalloying elements niobium and vanadium over a range of temperatures and strain rates penment to hot rolling. The fractional softening was evaluated by use of the offset method, which was confirmed to be a very reasonable method. Appropriate expressions are given for the static recrystallization kinetics as a function of temperature and strain rate. Particular attention is paid to the effect of strain rate on static recrystallization. It can be shown that the static softening is apparently accelerated by strain rate. Recrystallization in low temperature austenitic region is stopped due to precipitation of carbonitrides of microalloying elements, which is reflected in the form of a plateau in the curves of static softening.展开更多
A new highly efficient, visible light active, silver vanadate/polymeric carbonitride “core/shell” photocatalyst was prepared mechano-chemically prepared by grinding mixtures of <i><span><span style=&q...A new highly efficient, visible light active, silver vanadate/polymeric carbonitride “core/shell” photocatalyst was prepared mechano-chemically prepared by grinding mixtures of <i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate and mesoporous graphitic carbonitride. Besides the core/shell photocatalyst, </span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate/mesoporous polymeric carbonitride composites and supported mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span><span style="white-space:nowrap;">@</span></span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadates were prepared. The materials were characterized by transmission elec</span><span>tron microscopy (TEM), X-ray diffraction (XRD), nitrogen ad- and</span><span> de-sorption, diffuse reflectance UV-Vis measurement (DRS), infrared spectroscopy, Raman microscopy, and time-resolved photoluminescence spectroscopy. The photocatalytic performance of the materials was investigated in the degradation of organics using pharmaceutical ibuprofen and 4-(isobutyl phenyl) propionic acid sodium salt as model compounds under batch conditions. Reaction intermediates were studied by electrospray ionization and time-of-flight mass spectrometry (ESI-TOF-MS). Additionally, the degree of mineralization was determined by total organic carbon TOC measurements. The core/shell photocatalyst has shown superior photocatalytic activity compared to the other prepared composites or supported photocatalysts as well as the single mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span>. Scavenger experiments showed that valence band holes and anio</span><span>nic superoxide radicals are the main active species in the photocatalytic</span><span> process. TOC measurement confirmed the mineralization of the organic compound, which was in line with ESI-TOF-MS experiments. Time-resolved photoluminescence measurements indicated that charges generated in carbonitride migrate via diffusive hopping and exhibit increased mobility in the case of the silver vanadate/polymeric carbonitride composite.</span>展开更多
Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum ...Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum carbides or nitrides(MAX) phases,which is environmentally unfriendly.In this work,Ti_(3)AlCN MAX without HFetching was employed directly to observably enhance the kinetics and the cycling stability of MgH_(2).With addition of10 wt% Ti_(3)AlCN,the onset dehydrogenation temperature of MgH2 was dropped from 320 to 205℃,and the rehydrogenation of MgH2 under 6 MPa H2 began at as low as50℃.Furthermore,at 300℃,it could provide 6.2 wt% of hydrogen in 10 min.Upon cycling,the composite underwent an activation process during the initial 40 cycles,with the reversible capacity increased from 4.7 wt% to 6.5 wt%.After that,the capacity showed almost no attenuation for up to 100 cycles.The enhancing effect of Ti_(3)AICN on MgH_(2) was comparable to many MXenes.It was demonstrated that Ti_(3)AICN did not destabilize MgH_(2) but acted as an efficient catalyst for MgH_(2).Ti_(3)AICN was observed to be the active sites for the nucleation and growth of MgH_(2)and might also help in dissociation and recombination of hydrogen molecules.Such two factors are believed to contribute to the improvement of MgH_(2).This study not only provides a promising strategy for improving the hydrogen storage performances of MgH_(2) by using noncorrosive MAX materials,but also adds evidence of nucleation and growth of MgH_(2) on a catalyst.展开更多
Thermo-simulation test and transmission electron microscopy （TEM） have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite ...Thermo-simulation test and transmission electron microscopy （TEM） have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite deformation of C-Ti-Mo steel and C-Nb-Mo steel. The experimental results demonstrated that the austenitic structure was preserved both in C-Ti-Mo steel and C-Nb-Mo steel even if they were relaxed for 1000 s after deformation at 850℃. The strainqnduced precipitate occurs in two kinds of steel. Through the energy spectrum analysis, it was found that the precipitates were Ti（C, N） and Mo-bearing Nb（C, N） respectively and there exists a strong affinity of Mo for Nb with in the precipitates. Mo atoms would enter the lattice of Nb（C, N） particles probably after Nb（C, N） formation.展开更多
Titanium carbonitride (TiCN) coating was prepared on 45# carbon steel by electrical discharge coating (EDC), and the compositions, morphology and microstructure of the coating were studied. In addition, its friction a...Titanium carbonitride (TiCN) coating was prepared on 45# carbon steel by electrical discharge coating (EDC), and the compositions, morphology and microstructure of the coating were studied. In addition, its friction and wear behaviors relative to the physical vapor deposition (PVD) TiN coating were investigated. The results show that the TiCN coating features a thickness of 15μm with a primary phase of TiC 0.3 N 0.7 . The wear rates of the two coatings have no clear distinction at low applied loads. However, severe abrasive wear appears in the PVD TiN coating when the applied load exceeds 30 N, while the TiCN coating features better wear resistance. The abrasive wear with coating peelings is found to be the predominant wear mechanism at high applied loads.展开更多
基金supported by the Shanxi Provincial Basic Research Program(No.202403021221046)the National Natural Science Foundation of China(Nos.52004180 and 52204350)+5 种基金the China Postdoctoral Science Foundation(No.2020M683706XB)the Research Project Supported by Shanxi Scholarship Council of China(No.2023-080)the Fund Projects for the Central Government to Guide the Development of Local Science and Technology(No.236Z1023G)the Hebei Province High-level Talent Funding Project(No.B20231016)the National College Student Innovation and Entrepreneurship Training Program(No.202410112116)the Graduate Student Scientific Research Innovation Program(No.2024KY278).
文摘Invar steels possess excellent thermal expansion properties,making them suitable as materials for manufacturing precision instruments.However,conventional invar steels lack sufficient strength for engineering applications,and various strengthening methods are urgently needed to enhance their strength.In this work,the possibility of enhancing the strength and maintaining low coefficient of thermal expansion(CTE)of the steel through mechanical heat treatment and the introduction of vanadium carbonitride is demonstrated.V-N microalloying and various heat treatment processes enable invar steel to enhance its strength while maintaining low thermal expansion properties.The strength of low-nitrogen addition invar steel measured 593 MPa during direct aging,representing a 44.6% increase compared to invar steel.After undergoing cold-deformation aging,the strength of low-nitrogen invar steel increased to 790 MPa,indicating a substantial improvement in strength relative to the direct aging condition.Notably,the coefficient of thermal expansion remained at 0.98×10^(-6)℃^(-1).By further increasing N content to introduce more vanadium carbonitride,the strength of high-nitrogen invar steel reached 927 MPa under cold-deformation process while maintaining a low CTE value of 1.02×10^(-6)℃^(-1).This achieved an extraordinary balance of high strength and low CTE,which is due to a well combination of various strengthening mechanisms,especially the Orowan strengthening where dislocations continuously bypass vanadium carbonitride to achieve the strengthening effect.The resulting findings are important for future preparation of excellent properties invar steel in industrial applications.
基金financially supported by the Science and Technology Support Project of Jiangxi Province(No. 20112BBE50006)Young Scientists of Jiangxi Province Training Objects(No.20133BCB23032)
文摘Based on mass balance and solubility product equations, a thermodynamic model enabling the calcula- tion of equilibrium carbonitride composition and relative amounts as a function of steel composition and tem- perature was developed, which provides a method to es- timate the carbonitride complete dissolution temperature for different steel compositions. Actual carbonitride pre- cipitation behavior was further verified in Ti-V-C-N microalloyed steel system. The model suggests that for higher IV] and [Ti] dissolved in steels, it is available to decrease the addition of C and N during alloy composi- tion design. The resultant longer fatigue life of the modified steel could be attributed to the more [V] and [Ti] dissolved in the matrix, inducing finer dispersion of carbonitrides. Therefore, this model is proved to be effective in determining better chemical composition for high-performance steels, leading to possible reductions in the cost of production and improvements in the combined mechanical properties of the steels.
基金the China National Funds for Distinguished Young Scientists (No.51325401)the National High Technology Research and Development Program of China (No.2015AA042504)the National Natural Science Foundation of China (No.51474156) for financial support
文摘In this work, the growth kinetics of MX （M - metal, X - C/N） nanoprecipitates in type 347H austenitic steel was systematically studied. To investigate the coarsening behavior and the growth mechanism of MX carbonitrides during long-term aging, experiments were performed at 700, 800, 850, and 900℃ for different periods （1, 24, 70, and 100 h）. The precipitation behavior of carbonitrides in specimens subjected to various aging conditions was explored using carbon replicas and transmission electron microscopy （TEM） observations. The corresponding sizes ofMX carbonitrides were measured. The results demonstrates that MX carbonitrides precipitate in type 347H austenitic steel as Nb（C,N）. The coarsening rate constant is time-independent; however, an increase in aging temperature results in an increase in coarsening rate of Nb（C,N）. The coarsening process was analyzed according to the calculated diffusion activation energy of Nb（C,N）. When the aging temperature was 800-900℃, the mean activation energy was 294 kJ·mol -1, and the coarsening behavior was controlled primarily by the diffusion of Nb atoms.
文摘According to the misfitting dislocation theory,a method of theoretical calculation was devel- oped for the specific energy of the semicoherent interface between microalloy carbonitrides and austenite matrix.The calculating formulae were derived and the results were satisfactorily applied on the research works.
文摘The strain-induced isothermal precipitation and the law of coarsening of Nb,V and Ti carbonitrides in Nb-steel.V-steel.Nb-V steel and Ti-V-Nb steel have been investigated systematically by means of STEM,EDAX,a new extraction replica technique and the quanti- tative phase analyses method.
基金financially supported by the National Natural Science Foundation of China(No.52474355)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project,Nos.2022JH25/10200003 and 2023JH2/101800058)the Fundamental Research Funds for the Central Universities(Nos.N25YJS003 and N25DCG006)。
文摘The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence thethermoplasticity,thereby affecting the quality of the slab.In this work,a prediction model for two-stage austenite growth under varyingcooling rates was established by incorporating the effect of second-phase pinning and high-temperature ferrite-austenite phase transform-ation and growth theory.The results indicate that with 0.02wt%Ti,the high-temperature ferrite growth exhibits typical parabolic growthcharacteristics.When the Ti content increases to 0.04wt%,the high-temperature ferrite grain boundary migration rate significantly slowsduring the initial solidification stage.The predicted austenite grain sizes for 0.02wt%Ti microalloyed steel at the center,quarter,and sur-face of the slab are 5592,3529,and 1524μm,respectively.For 0.04wt%Ti microalloyed steel,the austenite grain sizes are 4074,2942,and 1179μm at the same positions.The average error is within 5%.As the Ti content increases from 0.02wt% to 0.04wt%,the austenitegrain refinement at the center is most significant,with an average grain size reduction of 27.14%.
文摘Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corrected from 1 to 2.The correct author affiliation has been provided in this Correction and the original article[1]has been corrected.
基金financially supported by the National Natural Science Foundation of China(No.51974078)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project,Nos.2022 JH25/10200003 and 2023 JH2/101800058)the Fundamental Research Funds for the Central Universities(No.N25YJS003).
文摘High temperature tensile were performed by using a thermo-mechanical GW1600 to simulate the deformation of Ti microalloy steels at high temperatures and low deformation rates similar to those during continuous casting.An equivalent austenite diameter was proposed,taking into account the weakening effects of proeutectoid ferrite films and Ti carbonitride precipitation.Based on this,a hot ductility prediction model for the slab was established to investigated hot ductility.The results show that as Ti content increases,the hot ductility of Ti microalloy steel initially increases and then decreases.At low Ti content,the pinning effect of Ti carbonitrides increases with the increase in Ti content,which inhibits grain coarsening for improving hot ductility.As Ti content increases,the size of carbonitrides grows,weakening the pinning effect and leading to austenite grain coarsening.Simultaneously,the formation of Ti carbonitrides inhibits proeutectoid ferrite film formation,leading to a reduction in its thickness.These combined factors reduce the hot ductility of the continuous casting steel.According to the hot ductility prediction model,in order of severity,the factors affecting hot ductility are:proeutectoid ferrite film,chain-like nanoscale Ti carbonitrides,austenite grain size,and dispersed nanoscale Ti carbonitrides.An accuracy error of less than 10%is shown by the model.
基金supported by the National Key R&D Program of China(Grant No.2021YFA0715803)the National Natural Science Foundation of China(Grant Nos.52293373 and 52130205)+3 种基金the Special Funds of the National Natural Science Foun-dation of China(Grant No.52342207)the National Science and Technology Major Project(Grant No.J2022-VI-0011-0042)the Joint Fund of Henan Province Science and Technology R&D Program(Grant No.225200810002)the Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory(Grant No.JCKYS2024607001-1).
文摘Hafnium carbonitride(HfC_(x)N_(1-x))ceramics have drawn considerable interest due to their exceptional me-chanical and thermophysical properties.Herein,we report a novel single-source precursor with Hf-N bonds as the main chain and fabricate HfC_(x)N_(1-x)ceramics after pyrolysis of the precursor.The synthesis,ceramic conversion,and microstructural evolution of the single-source precursor as well as the derived HfC_(x)N_(1-x)ceramics treated under various atmospheres were investigated.The results indicate that in an argon atmosphere,the nitrogen content within HfC_(x)N_(1-x)decreases with rising temperature.While under a nitrogen atmosphere,the high concentration of N_(2)facilitates the rapid conversion of HfO2 to Hf7O8N4,which subsequently promotes the transformation of the HfC_(x)N_(1-x)solid solution ceramics.During this process,there is also an inhibitory effect of N_(2)on the tendency of HfN into HfC.Moreover,the desired chemical composition of HfC_(x)N_(1-x)can be regulated by adjusting the N_(2)concentration in the heat treat-ment atmosphere.The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfC_(x)N_(1-x)ceramics.
基金Project supported by the National Natural Science Foundation of China
文摘The precipitation strengthening mechanism of microalloy carbonitrides (M(CN) phases) in ferrite is a basic research work on the precipitation strengthening behaviour of microalloy steels. Generally speaking, the precipitation strengthening effect is regarded as the result
基金This work is financially supported by Hebei Natural Science Foundation under Grant Nos.E2020402067,E2018402098,and E2021402056,Open Program of State Key Laboratory of Advanced Metallurgy under Grant No.K1:21-08Key Project of Handan Scientific Research Program under Grant No.21122015004the Science and Technology Research and Development Program of Handan City under Grant No.21422101235.The authors would like to express their sincere thanks to Tianjin CISRI-HARDER Materials&Technology Co.,Ltd.for the experiment.
文摘The morphology,size,quantity,and composition of complex oxide+carbonitride in H13 steel held at 1250℃for 5,10,and 15 h were determined.The results show that the ratio and number of complex carbonitrides with cores in H13 steel are gradually increased when holding at 1250℃compared with those in the original H13 steel,and the core size increases.There are one or more oxide cores in(Ti_(x),V_(1-x))(Cy,N_(1-y)),including xCaO·zAl_(2)O_(3),xCaO·yMgO·zAl_(2)O_(3),and CaO after holding at 1250℃,in addition to MgO·Al_(2)O_(3)and Al_(2)O_(3)in the original steel.The equilibrium temperature for(Ti_(x),V_(1-x))(Cy,N_(1-y))precipitation at the solidification front and decomposition in the solid state was theoretically analyzed,which was affected by the x value and the product of Ti and N contents in H13 steel.Meanwhile,the composition of(Ti_(x),V_(1-x))(Cy,N_(1-y))is influenced by the oxide cores.It is convinced that(Ti_(x),V_(1-x))(Cy,N_(1-y))with oxide cores has a higher stability,especially for oxides with a high Al_(2)O_(3)content.Heat treatment at high temperature facilitates a more reasonable analysis of oxide+carbonitride,and the generation mechanism of oxide+carbonitride was discussed.
基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:2023YJS061,2023JBZY019。
文摘Carbonitride MXenes,such as Ti_(3)CNT_(x),Ti_(2)C_(0.5)N_(0.5)T_(x),and Ti_(4)(C_(0.2)N_(0.8))_(3)T_(x),have attracted much interest in the large family of two-dimensional(2D)nanomaterials.Like their carbide MXene counterparts,the nanolayered structure and functional groups endow carbonitride MXenes with an attractive combination of physical and chemical properties.More interestingly,the replacement of C by N changes the lattice parameters and electron distribution of carbonitride MXenes due to the greater electronegativity of N as compared to C,thus resulting in significantly enhanced functional properties.This paper reviews the development of carbonitride MXenes,the preparation of 2D carbonitride MXenes,and the current understanding of the microstructure,electronic structure,and functional properties of carbonitride MXenes.In addition,applications,especially in energy storage,sensors,catalysts,electromagnetic wave shielding and absorption,fillers,and environmental and biomedical fields,are summarized.Finally,their current limitations and future opportunities are presented.
文摘As a new type of two-dimensional material,MXene’s unique layered structure,outstanding electrical conductivity,low density,tunable surface chemistry,and solution processability make it receive extensive attention in various fields,especially for the lightweight shielding mate rials since the report on electromagnetic interference(EMI) shielding of 2D Ti3 C2 Tx in 2016.In this review,the progress on the MXe nes material including their synthetic strategies,prope rties and EMI application is highlighted.First,the recent advance on the different synthesis methods and properties of MXene is summarized.According to their intrinsic characteristics,the application of MXene in EMI fields is then discussed.Finally,the challenges and perspective on the future development of MXene in low-cost preparation and practical application are proposed.
文摘The characteristics and generation mechanism of（Ti,Nb,V）（C,N） precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of（Ti,Nb,V）（C,N） phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich（Ti,Nb,V）（C,N） precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2–5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of（Ti,Nb,V）（C,N） is concentrated. The average composition of the single Ti-V-rich phase is（Ti_（0.511）V_（0.356）Nb_（0.133））（CxNy）, whereas that for the single Nb-rich phase is（Ti_（0.061）V_（0.263）Nb_（0.676））（C_xN_y）. The calculation results based on the Scheil–Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.
基金supported by the Fundamental Research Funds for the National Natural Science Foundation of China(No.52004059)the Program of Introducing Talents of Discipline to Universities(No.B21001)+1 种基金the Central Universities(No.N2125017)the Talent Project of Revitalizing Liaoning(No.XLYC1902046).
文摘Two martensitic stainless steels of 2Cr12Ni6 type hardened and tempered at 773 K have been studied:the first with 0.2%carbon content and the second with partial replacement of carbon by nitrogen(C0.1N0.1)in the first steel.It is found that the partial substitution of carbon with nitrogen contributed to an increase in ductility and strength of the steel,presumably due to the formation of more dispersive carbonitrides.Meanwhile,the addition of nitrogen suppressed the precipitation of carbonitrides,so that the solid solution strengthening effect of C0.1N0.1 did not decrease significantly after tempering treatment.In addition,the partial replacement of carbon by nitrogen contributed to improved ability against pitting corrosion(PC)in chloride-containing medium(3.5%NaCl at 303 K).The higher resistance to PC of tempered nitrogen-containing steel is apparently due to the lower content of massive carbonitrides,especially the reduced aggregation at grain boundaries.This leads to a lower acidity and aggressiveness of the test solution near the sample surface due to the accumulation of NH4^(+) ammonium ions in it.As a result of nitrogen addition,exception for Cr_(23)C_(6) and VC,Cr_(2)N and(Cr,V)N type precipitates have also been found in C0.1N0.1 steel and this is consistent with the thermodynamic calculation results.In conclusion,substituting carbon by nitrogen in traditional martensitic stainless steel could realize the simultaneous improvement of multiple properties of martensitic stainless steels.This result provides a promising composition optimization route to develop novel martensitic stainless steels.
文摘Double-hit compression tests were performed on StE460 steel containing microalloying elements niobium and vanadium over a range of temperatures and strain rates penment to hot rolling. The fractional softening was evaluated by use of the offset method, which was confirmed to be a very reasonable method. Appropriate expressions are given for the static recrystallization kinetics as a function of temperature and strain rate. Particular attention is paid to the effect of strain rate on static recrystallization. It can be shown that the static softening is apparently accelerated by strain rate. Recrystallization in low temperature austenitic region is stopped due to precipitation of carbonitrides of microalloying elements, which is reflected in the form of a plateau in the curves of static softening.
文摘A new highly efficient, visible light active, silver vanadate/polymeric carbonitride “core/shell” photocatalyst was prepared mechano-chemically prepared by grinding mixtures of <i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate and mesoporous graphitic carbonitride. Besides the core/shell photocatalyst, </span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadate/mesoporous polymeric carbonitride composites and supported mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span><span style="white-space:nowrap;">@</span></span><i><span><span style="white-space:nowrap;">β</span></span></i><span>-silver vanadates were prepared. The materials were characterized by transmission elec</span><span>tron microscopy (TEM), X-ray diffraction (XRD), nitrogen ad- and</span><span> de-sorption, diffuse reflectance UV-Vis measurement (DRS), infrared spectroscopy, Raman microscopy, and time-resolved photoluminescence spectroscopy. The photocatalytic performance of the materials was investigated in the degradation of organics using pharmaceutical ibuprofen and 4-(isobutyl phenyl) propionic acid sodium salt as model compounds under batch conditions. Reaction intermediates were studied by electrospray ionization and time-of-flight mass spectrometry (ESI-TOF-MS). Additionally, the degree of mineralization was determined by total organic carbon TOC measurements. The core/shell photocatalyst has shown superior photocatalytic activity compared to the other prepared composites or supported photocatalysts as well as the single mpg-C</span><sub><span>3</span></sub><span>N</span><sub><span>4</span></sub><span>. Scavenger experiments showed that valence band holes and anio</span><span>nic superoxide radicals are the main active species in the photocatalytic</span><span> process. TOC measurement confirmed the mineralization of the organic compound, which was in line with ESI-TOF-MS experiments. Time-resolved photoluminescence measurements indicated that charges generated in carbonitride migrate via diffusive hopping and exhibit increased mobility in the case of the silver vanadate/polymeric carbonitride composite.</span>
基金financially supported by the Science and Technology Department of Guangxi Zhuang Autonomous (No.GuiKeAD21238022)the Natural Science Foundation of Guangxi Province (No.2019GXNSFBA185004)National Natural Science Foundation of China (Nos.52001079,51961005 and 52261038)。
文摘Many MXenes are efficient catalysts for MgH_(2)hydrogen storage material.Nevertheless,the synthesis of MXenes should consume a large amount of corrosive HF to etch out the Al layers from the transition metal aluminum carbides or nitrides(MAX) phases,which is environmentally unfriendly.In this work,Ti_(3)AlCN MAX without HFetching was employed directly to observably enhance the kinetics and the cycling stability of MgH_(2).With addition of10 wt% Ti_(3)AlCN,the onset dehydrogenation temperature of MgH2 was dropped from 320 to 205℃,and the rehydrogenation of MgH2 under 6 MPa H2 began at as low as50℃.Furthermore,at 300℃,it could provide 6.2 wt% of hydrogen in 10 min.Upon cycling,the composite underwent an activation process during the initial 40 cycles,with the reversible capacity increased from 4.7 wt% to 6.5 wt%.After that,the capacity showed almost no attenuation for up to 100 cycles.The enhancing effect of Ti_(3)AICN on MgH_(2) was comparable to many MXenes.It was demonstrated that Ti_(3)AICN did not destabilize MgH_(2) but acted as an efficient catalyst for MgH_(2).Ti_(3)AICN was observed to be the active sites for the nucleation and growth of MgH_(2)and might also help in dissociation and recombination of hydrogen molecules.Such two factors are believed to contribute to the improvement of MgH_(2).This study not only provides a promising strategy for improving the hydrogen storage performances of MgH_(2) by using noncorrosive MAX materials,but also adds evidence of nucleation and growth of MgH_(2) on a catalyst.
基金Item Sponsored by Natural Science Foundation of Hebei Province of China (E2008001141)
文摘Thermo-simulation test and transmission electron microscopy （TEM） have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite deformation of C-Ti-Mo steel and C-Nb-Mo steel. The experimental results demonstrated that the austenitic structure was preserved both in C-Ti-Mo steel and C-Nb-Mo steel even if they were relaxed for 1000 s after deformation at 850℃. The strainqnduced precipitate occurs in two kinds of steel. Through the energy spectrum analysis, it was found that the precipitates were Ti（C, N） and Mo-bearing Nb（C, N） respectively and there exists a strong affinity of Mo for Nb with in the precipitates. Mo atoms would enter the lattice of Nb（C, N） particles probably after Nb（C, N） formation.
基金Project(51075075)supported by the National Natural Science Foundation of China
文摘Titanium carbonitride (TiCN) coating was prepared on 45# carbon steel by electrical discharge coating (EDC), and the compositions, morphology and microstructure of the coating were studied. In addition, its friction and wear behaviors relative to the physical vapor deposition (PVD) TiN coating were investigated. The results show that the TiCN coating features a thickness of 15μm with a primary phase of TiC 0.3 N 0.7 . The wear rates of the two coatings have no clear distinction at low applied loads. However, severe abrasive wear appears in the PVD TiN coating when the applied load exceeds 30 N, while the TiCN coating features better wear resistance. The abrasive wear with coating peelings is found to be the predominant wear mechanism at high applied loads.
