Grain boundary segregation(GBS)of solutes influences the grain size,texture,and strength of Mg wrought alloys.So far,solutes'GBS in Mg has mostly been investigated by qualitative experimental observations.In this ...Grain boundary segregation(GBS)of solutes influences the grain size,texture,and strength of Mg wrought alloys.So far,solutes'GBS in Mg has mostly been investigated by qualitative experimental observations.In this work,we develop a quantitative model to compute the grain boundary segregation energy(ΔE_(seg))in binary Mg based alloys that takes the relative atomic density of GB into account.The model is utilized to computeΔE_(seg)of Al,Zn,Ca,Sn,Y,Gd,and Nd solutes in Mg.The result suggests that rare earth elements and Ca are more prone to GBS than Al,Zn,and Sn.Segregation of Gd solutes can explain the smaller grain size and slower grain growth in Mg-Gd extruded alloys than Mg-Al and Mg-Zn counterparts.It also provides an explanation for the weak extrusion texture in Mg-Gd.展开更多
Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymme...Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymmetric tilt boundaries are hard to be accounted for based on traditional theoretical models,and the corresponding solute segregation is complex.Herein,atomic structures of a specific asymmetric boundary on{1012}TBs were reveled using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),molecular dynamics(MD)and density functional theory(DFT)simulations.Reaction between<a60>M dislocations and the{1012}TB can generate a~61°/25°asymmetric tilt boundary.The segregation of Gd and Zn atoms is closely related to the aggregateddislocations and the interfacial interstices of the asymmetric tilt boundary,which is energetically favorable in reducing the total system energy.展开更多
Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated...Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated the segregation behaviors of an Mg-RE alloy under deformation.We found that the enrichment of solute atoms occurred in{101^(-)1}compressive twin boundaries under compression at 298 K without any annealing in an Mg-RE alloy by scanning transmission electron microscopy and energy-dispersive X-ray analysis.The segregated solutes and precipitates impeded the twin growth,partially contributing to the formation of small-sized{101^(-)1}compressive twins.This research indicates the twin boundaries can be strengthened by segregated solutes and precipitates formed under deformation at room temperature.展开更多
This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo sim...This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo simulations.Two segregation mechanisms,substitutional and interstitial mechanisms,are observed.The intergranular defects,including dislocations,steps and vacancies,and the intervals in structural units are conductive to the prevalence of interstitial mechanism.And substitutional mechanism is favored by the highly ordered twin GBs.Furthermore,the two mechanisms affect the GB structure differently.It is quantified that interstitial mechanism is less destructive to GB structure than substitutional one,and often leads to a segregation level being up to about 6 times higher than the latter.These findings contribute to atomic scale insights into the microscopic mechanisms about how solute atoms are absorbed by GB structures,and clarify the correlation among intergranular structures,segregation mechanisms and kinetics.展开更多
First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P atα-FeΣ3(111)[11¯0]symmetrical tilt grain boundary(GB).Results dem...First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P atα-FeΣ3(111)[11¯0]symmetrical tilt grain boundary(GB).Results demonstrate that both P and Mg are segregated at GB,and P has a stronger segregation potency.Mg prefers to substitute at grain boundary plane with the largest absorbable vacancy,whereas P inclines to substitute at the sites near Fe atoms to form strong covalent Fe-P bonds.When Mg exists at GB,the segregation behavior of P may be greatly inhibited by the decrease in possible solution sites and the increase in segregation energy.P has stronger interactions with Mg at GB,forming a lower energy hybridization peak.These results can be used to explain why the addition of a small amount of Mg can ameliorate the temper embrittlement phenomenon.展开更多
Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb al...Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb alloy at different temperatures.By analyzing its pair correlation function(PCF),bond pairs,bond angle distribution function(BADF),and Voronoi polyhedron(VP),the short-range order(SRO)of the alloy was investigated.In the Sb melt,the solute atoms Cu and Fe,which have smaller distribution coefficients,exhibit a stronger affinity for Sb than the solute atoms As and Bi,which have larger distribution coefficients.The BADF of As and Bi with larger distribution coefficients shows a lower probability of small-angle peaks compared to large-angle peaks,whereas the BADF of Cu and Fe with smaller distribution coefficients exhibits the opposite trend.The BADF reveals that Sb-As and Sb-Bi approach pure Sb melt,while Sb-Cu and Sb-Fe deviate significantly.Compared to Sb-Cu and Sb-Fe,the Sb-As and Sb-Bi systems exhibit more low-index bonds,suggesting weaker interactions and more disorder.The VP fractions around As and Bi atoms are lower than those around Cu and Fe,and the VP face distributions around As and Bi are more complex.There are differences in the VP around different solute atoms,primarily due to the varying bond pair fractions associated with each solute atom.Fe has the smallest diffusion coefficient,primarily due to its compact local structure.展开更多
In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followe...In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followed by annealing,with a low anisotropy in mechanical properties.More importantly,the HPR-annealed alloy shows an excellent formability at the same time,i.e.,the index Erichsen(I.E.)value reaches 7.9 mm(the Erichsen cupping test)at room temperature,which is higher compared with the Mg-1.8Zn-0.3Y-0.3Ca0.3Zr alloy produced by conventional multi-pass rolling(CR)followed by annealing.The excellent synergy of strength and formability of the HPR-annealed alloy is mainly attributed to a weak elliptical ring texture,as well as finer and denser Zn_(2)Zr_(3)precipitates.The formation of weak elliptical ring texture is related to the preferential co-segregation of Zn and Ca elements at boundaries of basal grains with smal misorientation angles during annealing,which inhibits the growth of basal grains and promotes the preferential growth of non-basal grains At the same time,in comparison with the CR-annealed alloy,the HPR-annealed alloy contains finer and denser Zn_(2)Zr_(3)precipitates that ar less likely to become sources of cracks,leading to the higher strength and formability of the HPR-annealed alloy.The results in this work can provide reference for the development of high strength Mg alloy sheets with excellent room temperature formability,which also shed light on mitigating planar anisotropy in mechanical properties for Mg alloy sheets.展开更多
Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been...Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been widely studied as an active cathode but still suffer from serious detrimental segregations.To enhance the cathode stability,a PBCC derived A-site medium-entropy Pr_(0.6)La_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Ba_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(ME-PBCC)oxide was prepared and its segregation behaviors were investigated under different conditions.Compared with initial PBCC oxide,the segregations of BaO and Co_(3)O_(4)on the surface of ME-PBCC material are significantly suppressed,especially for Co_(3)O_(4),which is attributed to its higher configuration entropy.Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material,enabling it as a promising cathode for SOFCs.展开更多
A novel core-shell structured Al_(8)Mn_(4)Y-Al_(2)Ca phase and controllable solute-segregation are elaborately designed in dilute Mg-0.6Al-0.5Mn-0.1Ca-0.1Y alloy(wt.%),via incomplete peritectic transformation during t...A novel core-shell structured Al_(8)Mn_(4)Y-Al_(2)Ca phase and controllable solute-segregation are elaborately designed in dilute Mg-0.6Al-0.5Mn-0.1Ca-0.1Y alloy(wt.%),via incomplete peritectic transformation during twin-roll casting.When soaked in 3.5 wt.%NaCl solution,Al_(2)Ca shell with a low electrochemical potential prevents direct contact of noble Al_(8)Mn_(4)Y with Mg matrix,mitigating the micro-galvanic corrosion and meanwhile accelerating the formation of uniform corrosion film.Thereafter,solute(Al,Ca)-segregation motivates the formation of heterogeneous multilayered corrosion product films,enhancing corrosion resistance and even achieving self-healing upon long-term corrosion.Notably,the dilute Mg alloy exhibits a corrosion rate as low as 0.22±0.05 mm·y^(−1).展开更多
The crankshaft is subjected to complex rotational centrifugal force,periodic gas inertia force,and reciprocating inertia force during its working process.Consequently,the homogeneity requirement for crankshaft steel i...The crankshaft is subjected to complex rotational centrifugal force,periodic gas inertia force,and reciprocating inertia force during its working process.Consequently,the homogeneity requirement for crankshaft steel is exceptionally high.The distribution characteristics of center segregation and spot segregation of continuous casting bloom 42CrMoA crankshaft steel were analyzed by experiments,and the control mechanism of spot segregation by soft reduction zone and reduction amount was discussed.When the center solid fraction is between 0.61 and 1.00,an 8-mm soft reduction has a negligible impact on the flow of liquid steel at the end of solidification.Although it effectively improves center segregation,the improvement of spot segregation is limited.On the other hand,when the center solid fraction is between 0.31 and 1.00,a reduction of 10–12 mm,along with an expanded reduction zone and increased reduction amount,significantly promotes the flow of liquid steel at the end of solidification,reduces the size of equiaxed grains,mitigates the center negative segregation,and decreases the maximum size of spot segregation from 2954.29 to 1354.07μm.The number of spot segregations and the solutes enrichment degree of C,Cr,and Mn have also been significantly improved.An appropriate soft reduction zone and reduction amount can markedly ameliorate the semi-macro spot segregation of crankshaft steel blooms,thereby providing high-quality raw materials for subsequent products and enhancing the competitiveness of crankshaft products.展开更多
The microstructure and mechanical properties of the compact strip production(CSP)processed quenching and partitioning(Q&P)steels were investigated through experimental methods to address the challenge of designing...The microstructure and mechanical properties of the compact strip production(CSP)processed quenching and partitioning(Q&P)steels were investigated through experimental methods to address the challenge of designing high-performance Q&P steels.Compared with the conventional process(CP)produced samples,with slightly reduced strength,the total elongation of the CSP produced samples was increased by nearly 7%.Microstructural analysis revealed that variations in austenite stability were not the primary cause for the differences in mechanical properties between the CSP and the CP.The CSP processed Q&P steel exhibited milder center segregation behavior in contrast to the CP processed Q&P steel.Consequently,in the CSP processed Q&P steel,a higher proportion of austenite and a lower proportion of martensite were observed at the center position,delaying the crack initiation in the central region and contributing to the enhanced ductility.The investigation into the CSP process reveals its effect on alleviation of segregation and enhancement of mechanical properties of the Q&P steel.展开更多
The elemental segregation,microstructure,and mechanical properties of thermo-mechanical control process(TMCP)treated high-manganese wear-resistant steel(HMWS)were experimentally investigated.Firstly,the initial elemen...The elemental segregation,microstructure,and mechanical properties of thermo-mechanical control process(TMCP)treated high-manganese wear-resistant steel(HMWS)were experimentally investigated.Firstly,the initial elemental segregation in the continuous casting slab of HMWS was characterized using the original position analysis.The results showed that the elemental segregation predominantly occurred near the quarter and the center regions of the slab.The homogenization of manganese(Mn)in the slab was not as obvious as that of other elements after the heating process.Subsequently,a series of hot-rolling tests were carried out on HMWS slab samples under different TMCP conditions,and the elemental segregation and microstructure of the TMCP-treated HMWS were investigated by microscopic analysis methods.The findings demonstrated that the segregations of carbon and silicon were effectively eliminated after the TMCP treatment,while Mn segregation presented a band-shaped arrangement and could be reduced at lower finishing rolling temperatures.The matrix phase of HMWS remained austenite regardless of the TMCP conditions,and the average size of austenite grains increased with the increasing finishing rolling temperature.Carbide particles were observed to form within austenite grains and even along grain boundaries at higher coiling temperatures.Finally,the mechanical tests were performed on the TMCP-treated HMWS at room temperature.The mechanical properties including tensile stress,yield stress,Charpy impact energy,and microhardness were discussed considering the effects of Mn segregation band,microstructure,and carbide precipitation.展开更多
The effect of high pressure on the microstructure and microsegregation of Mg-11Al(mass fraction,%)alloys was studied through experiments and first-principles calculations.The results show that the Al content in the in...The effect of high pressure on the microstructure and microsegregation of Mg-11Al(mass fraction,%)alloys was studied through experiments and first-principles calculations.The results show that the Al content in the initial solid phase is high owing to the high solute partition coefficient and the large undercooling in the alloys solidified under pressures of 4-6 GPa,and the Al content in the initial solid phase increases with the increase of pressure.Consequently,the total amount of excess solute in the liquid phase in the final solidification stage decreases with increasing pressure,thus decreasing or suppressing the eutectic transformation.Furthermore,the microstructure of the alloys solidified under pressures of 5-6 GPa is a fine-grained solid solution,consisting of grains with high solubility of Al atoms and grain boundaries with abundant Al solutes.As the pressure increases,the grain boundary doping energy of Al atoms decreases,while their grain boundary segregation energy of Al atoms increases,and the charge density between the Mg-Al(Mg)bonds also rises.Therefore,the stability of the microstructure is improved,and the bond strength of grain boundaries is enhanced.展开更多
This study investigates the impact of Zn alloying on the dispersion of the reinforcing particle in Mg_(2)Sn/Mg composites.In the composite,Zn manifests in three distinct forms:Zn segregation layer between Mg–Mg_(2)Sn...This study investigates the impact of Zn alloying on the dispersion of the reinforcing particle in Mg_(2)Sn/Mg composites.In the composite,Zn manifests in three distinct forms:Zn segregation layer between Mg–Mg_(2)Sn,the solid solution and the MgZn_(2)phase.First-principles calculations confirm that the formation of Zn segregation layer decreases the interfacial energy of the Mg–Mg_(2)Sn.Importantly,this segregation layer significantly enhances the comigration capability of Mg_(2)Sn particles with Mg matrix during sintering flow,effectively hindering the agglomeration and coarsening of the nano-sized reinforcing phase.The dense and uniformly distributed nano-sized Mg_(2)Sn significantly increases the activity of non-basal slip,ensuring good elongation of the composite while enhancing strength.It can be concluded that enhancing the comigration-ability of reinforcing particles with the matrix is an effective strategy for achieving controlled dispersion of high-volume reinforcing particles and an excellent combination of strength and ductility in magnesium matrix composites.展开更多
Utilizing coarse aggregates containing mining waste rock for backfilling addresses the strength requirements and reduces the expenses associated with binder and solid waste treatment.However,this type of material is p...Utilizing coarse aggregates containing mining waste rock for backfilling addresses the strength requirements and reduces the expenses associated with binder and solid waste treatment.However,this type of material is prone to aggregate segregation,which can lead to uneven deformation and damage to the backfill.We employed an image-segmentation method that incorporated machine learning to analyze the distribution information of the aggregates on the splitting surface of the test blocks.The results revealed a nonlinear rela-tionship between aggregate segregation and variations in solid concentration(SC)and cement/aggregate ratio(C/A).The SC of 81wt%-82wt%and C/A of 10.00wt%-12.50wt%reflect surges in fluid dynamics,friction effects,and shifts in their dominance.A uniaxial compression experiment,supplemented with additional strain gauges and digital image correlation technology,enabled us to analyze the mechanical properties and failure mechanism under the influence of aggregate segregation.It was found that the uniaxial compressive strength,ranging from 1.75 MPa to 12.65 MPa,is linearly related to both the SC and C/A,and exhibits no significant relation-ship with the degree of segregation in numerical terms.However,the degree of segregation affects the development trend of the elastic modulus to a certain extent,and a standard deviation of the aggregate area ratio of less than 1.63 clearly indicates a higher elastic modu-lus.In the pouring direction,the top area of the test block tended to form a macroscopic fracture surface earlier.By contrast,the compressibility of the bottom area was greater than that of the top area.The intensification of aggregate segregation widened the differences in the deformation and failure characteristics between the different areas.For samples with different uniformities,significant differences in local deformation ranging from 515.00μεto 1693.70μεwere observed during the stable deformation stage.The extreme unevenness of the aggregate leads to rapid crack penetration in the sample,causing macroscopic tensile failure and resulting in premature structural failure.展开更多
As a rare earth solute element in Mg alloys,Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture.To achieve a more fundamental understanding ...As a rare earth solute element in Mg alloys,Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture.To achieve a more fundamental understanding on how Y addition affects the microstructural evolution and mechanical properties,the Y segregation behavior at grain boundaries was investigated in Mg-1wt.%Y and Mg-7wt.%Y alloys at different conditions.The segregation intensity and its dependence on the grain boundary misorientation angle were experimentally characterized and computationally predicted.Strong segregation at grain boundaries was observed in both low and high Y-containing alloys.Y segregation was found to remain in alloy Mg-7Y after high-temperature annealing heat treatment at 540℃.No direct correlation between the Y segregation intensity and the grain boundary misorientation angle could be established based on either the experimental characterization or the atomistic simulation with a spectral model.We thus conclude that grain boundary segregation of Y is independent of grain boundary misorientation angle.展开更多
In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then hea...In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Zn atoms along both high and lowangle grain boundaries(GBs).As compared with as-rolled plate,the yield strength,ultimate tensile strength,and the elongation of annealed sample is increased by 15.6%,14%,and 8.4%,respectively,acquiring an obvious strength-ductility synergy effect.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects including dislocation annihilation and grain coarsening.Meanwhile,the directional migration of Zn atoms and the annihilation of dislocations provide a"clear"space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.展开更多
Interface segregation of solute atoms has a profound effect on properties of engineering alloys.In this study,we report a novel strategy for breaking the strength-ductility dilemma of Mg alloy via solute segregation.T...Interface segregation of solute atoms has a profound effect on properties of engineering alloys.In this study,we report a novel strategy for breaking the strength-ductility dilemma of Mg alloy via solute segregation.The hot extruded Mg-1.8Gd-0.3Zr(wt.%)alloy sheet was subjected to three different passes of rolling,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Gd atoms along high and low-angel grain boundaries(GBs).Under almost precipitation-free conditions,the strength and ductility of rolled alloy sheets are simultaneously improved after annealing.Especially for the annealed 3-passes-rolled specimen,the yield strength,ultimate tensile strength,and elongation are simultaneously increased by 11.2%,7.3%,and 18%,respectively.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects,including dislocation annihilation and grain coarsening during the heating.Meanwhile,the directional migration of Gd atoms and the annihilation of dislocations provide a“clear”space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.展开更多
Wide-bandgap mixed-halide perovskites,particularly CsPbIBr_(2),hold great promise for multi-junction solar cells due to their well-matched bandgap and all-inorganic material system.However,their inherent susceptibilit...Wide-bandgap mixed-halide perovskites,particularly CsPbIBr_(2),hold great promise for multi-junction solar cells due to their well-matched bandgap and all-inorganic material system.However,their inherent susceptibility to light-induced phase segregation(LIPS)limits efficiency and stability.In this work,we investigate the effect of three organic additives-4-cyclopentene-1,3-dione(CPD),maleimide(HPD),and 3,4-dibromo-1H-pyrrole-2,5(2H,5H)-dione(BrPD)-on LIPS in wide-bandgap CsPbIBr_(2)perovskite films.The additives form various chemical interactions,including coordination bonds,hydrogen bonds,and ionic bonds,with I^(-)and undercoordinated Pb^(2+)ions,among which BrPD has the strongest interaction.This interaction regulates crystallization and improves film morphology.The BrPD-modified films have the largest grain size and the highest light stability,suppressing LIPS,enhancing carrier transfer,and improving device performance.BrPD-modified CsPbIBr_(2)-based solar cells achieve a power conversion efficiency(PCE)of 11.34%,outperforming the control(8.96%)and other additives.Moreover,BrPDmodified devices show excellent stability,retaining 94%of their initial PCE after 60 min of continuous light exposure.This work highlights the potential of strategically selected organic additives to enhance the stability and performance of perovskite solar cells,offering valuable insights for the design of high-efficiency and long-lasting perovskite-based optoelectronic devices.展开更多
Grain boundary(GB)segregation substantially influences the mechanical properties and performance of magnesium(Mg).Atomic-scale modeling,typically using ab-initio or semi-empirical approaches,has mainly focused on GB s...Grain boundary(GB)segregation substantially influences the mechanical properties and performance of magnesium(Mg).Atomic-scale modeling,typically using ab-initio or semi-empirical approaches,has mainly focused on GB segregation at highly symmetric GBs in Mg alloys,often failing to capture the diversity of local atomic environments and segregation energies,resulting in inaccurate structure-property predictions.This study employs atomistic simulations and machine learning models to systematically investigate the segregation behavior of common solute elements in polycrystalline Mg at both 0 K and finite temperatures.The machine learning models accurately predict segregation thermodynamics by incorporating energetic and structural descriptors.We found that segregation energy and vibrational free energy follow skew-normal distributions,with hydrostatic stress,an indicator of excess free volume,emerging as an important factor influencing segregation tendency.The local atomic environment's flexibility,quantified by flexibility volume,is also crucial in predicting GB segregation.Comparing the grain boundary solute concentrations calculated via the Langmuir-Mc Lean isotherm with experimental data,we identified a pronounced segregation tendency for Nd,highlighting its potential for GB engineering in Mg alloys.This work demonstrates the powerful synergy of atomistic simulations and machine learning,paving the way for designing advanced lightweight Mg alloys with tailored properties.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB3702602)the National Natural Science Foundation of China(Nos.51825101,52425101)。
文摘Grain boundary segregation(GBS)of solutes influences the grain size,texture,and strength of Mg wrought alloys.So far,solutes'GBS in Mg has mostly been investigated by qualitative experimental observations.In this work,we develop a quantitative model to compute the grain boundary segregation energy(ΔE_(seg))in binary Mg based alloys that takes the relative atomic density of GB into account.The model is utilized to computeΔE_(seg)of Al,Zn,Ca,Sn,Y,Gd,and Nd solutes in Mg.The result suggests that rare earth elements and Ca are more prone to GBS than Al,Zn,and Sn.Segregation of Gd solutes can explain the smaller grain size and slower grain growth in Mg-Gd extruded alloys than Mg-Al and Mg-Zn counterparts.It also provides an explanation for the weak extrusion texture in Mg-Gd.
基金supported by the Scientific and Technological Developing Scheme of Jilin Province under grants no.YDZJ202301ZYTS538the Chinese Academy of Sciences Youth Innovation Promotion Association under grants number 2023234+3 种基金the National Natural Science Foundation of China under grants number U21A20323the Scientific and Technological Developing Scheme of Jilin Province under grants no.SKL202302038the Major Scientific and Technological Projects of Hebei Province under grants No.23291001Zthe Scientific and Technology Project of Hanjiang District.
文摘Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymmetric tilt boundaries are hard to be accounted for based on traditional theoretical models,and the corresponding solute segregation is complex.Herein,atomic structures of a specific asymmetric boundary on{1012}TBs were reveled using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),molecular dynamics(MD)and density functional theory(DFT)simulations.Reaction between<a60>M dislocations and the{1012}TB can generate a~61°/25°asymmetric tilt boundary.The segregation of Gd and Zn atoms is closely related to the aggregateddislocations and the interfacial interstices of the asymmetric tilt boundary,which is energetically favorable in reducing the total system energy.
基金support from Interdisciplinary Research Project for Young Teachers of USTB Fundamental Research Funds for the Central Universities(Grant no.FRF-IDRY-23-030).
文摘Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated the segregation behaviors of an Mg-RE alloy under deformation.We found that the enrichment of solute atoms occurred in{101^(-)1}compressive twin boundaries under compression at 298 K without any annealing in an Mg-RE alloy by scanning transmission electron microscopy and energy-dispersive X-ray analysis.The segregated solutes and precipitates impeded the twin growth,partially contributing to the formation of small-sized{101^(-)1}compressive twins.This research indicates the twin boundaries can be strengthened by segregated solutes and precipitates formed under deformation at room temperature.
基金supported by grants from the National Natural Science Foundation of China(Nos.52031017,51801237)the National Key Laboratory of Science and Technology on High-strength Structural Materials in Central South University,China(No.6142912200106).
文摘This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo simulations.Two segregation mechanisms,substitutional and interstitial mechanisms,are observed.The intergranular defects,including dislocations,steps and vacancies,and the intervals in structural units are conductive to the prevalence of interstitial mechanism.And substitutional mechanism is favored by the highly ordered twin GBs.Furthermore,the two mechanisms affect the GB structure differently.It is quantified that interstitial mechanism is less destructive to GB structure than substitutional one,and often leads to a segregation level being up to about 6 times higher than the latter.These findings contribute to atomic scale insights into the microscopic mechanisms about how solute atoms are absorbed by GB structures,and clarify the correlation among intergranular structures,segregation mechanisms and kinetics.
文摘First-principles theory calculations were used to investigate the segregation behavior of P and Mg as well as the interactions between Mg and P atα-FeΣ3(111)[11¯0]symmetrical tilt grain boundary(GB).Results demonstrate that both P and Mg are segregated at GB,and P has a stronger segregation potency.Mg prefers to substitute at grain boundary plane with the largest absorbable vacancy,whereas P inclines to substitute at the sites near Fe atoms to form strong covalent Fe-P bonds.When Mg exists at GB,the segregation behavior of P may be greatly inhibited by the decrease in possible solution sites and the increase in segregation energy.P has stronger interactions with Mg at GB,forming a lower energy hybridization peak.These results can be used to explain why the addition of a small amount of Mg can ameliorate the temper embrittlement phenomenon.
文摘Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb alloy at different temperatures.By analyzing its pair correlation function(PCF),bond pairs,bond angle distribution function(BADF),and Voronoi polyhedron(VP),the short-range order(SRO)of the alloy was investigated.In the Sb melt,the solute atoms Cu and Fe,which have smaller distribution coefficients,exhibit a stronger affinity for Sb than the solute atoms As and Bi,which have larger distribution coefficients.The BADF of As and Bi with larger distribution coefficients shows a lower probability of small-angle peaks compared to large-angle peaks,whereas the BADF of Cu and Fe with smaller distribution coefficients exhibits the opposite trend.The BADF reveals that Sb-As and Sb-Bi approach pure Sb melt,while Sb-Cu and Sb-Fe deviate significantly.Compared to Sb-Cu and Sb-Fe,the Sb-As and Sb-Bi systems exhibit more low-index bonds,suggesting weaker interactions and more disorder.The VP fractions around As and Bi atoms are lower than those around Cu and Fe,and the VP face distributions around As and Bi are more complex.There are differences in the VP around different solute atoms,primarily due to the varying bond pair fractions associated with each solute atom.Fe has the smallest diffusion coefficient,primarily due to its compact local structure.
基金Tral Science Foundation of China(Nos.52271103,52334010and 52271031)Partial financial support came from JilinScientific and Technological Development Program(No.20220301026GX)Program for the Central UniversityYouth Innovation Team。
文摘In this work,a good balance of strength and ductility(a yield strength of 185 MPa and a uniform elongation of 20%)has been obtained in a dilute Mg-1.8Zn-0.3Y-0.3Ca-0.3Zr(wt.%)alloy using hard plate rolling(HPR)followed by annealing,with a low anisotropy in mechanical properties.More importantly,the HPR-annealed alloy shows an excellent formability at the same time,i.e.,the index Erichsen(I.E.)value reaches 7.9 mm(the Erichsen cupping test)at room temperature,which is higher compared with the Mg-1.8Zn-0.3Y-0.3Ca0.3Zr alloy produced by conventional multi-pass rolling(CR)followed by annealing.The excellent synergy of strength and formability of the HPR-annealed alloy is mainly attributed to a weak elliptical ring texture,as well as finer and denser Zn_(2)Zr_(3)precipitates.The formation of weak elliptical ring texture is related to the preferential co-segregation of Zn and Ca elements at boundaries of basal grains with smal misorientation angles during annealing,which inhibits the growth of basal grains and promotes the preferential growth of non-basal grains At the same time,in comparison with the CR-annealed alloy,the HPR-annealed alloy contains finer and denser Zn_(2)Zr_(3)precipitates that ar less likely to become sources of cracks,leading to the higher strength and formability of the HPR-annealed alloy.The results in this work can provide reference for the development of high strength Mg alloy sheets with excellent room temperature formability,which also shed light on mitigating planar anisotropy in mechanical properties for Mg alloy sheets.
基金Project supported by the National Natural Science Foundation of China(22279025,21773048,52302119)the Fundamental Research Funds for the Central Universities(2023FRFK06005,HIT.NSRIF202204)。
文摘Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells(SOFCs).The double perovskite oxide PrBa_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(PBCC)has been widely studied as an active cathode but still suffer from serious detrimental segregations.To enhance the cathode stability,a PBCC derived A-site medium-entropy Pr_(0.6)La_(0.1)Nd_(0.1)Sm_(0.1)Gd_(0.1)Ba_(0.8)Ca_(0.2)Co_(2)O_(5+δ)(ME-PBCC)oxide was prepared and its segregation behaviors were investigated under different conditions.Compared with initial PBCC oxide,the segregations of BaO and Co_(3)O_(4)on the surface of ME-PBCC material are significantly suppressed,especially for Co_(3)O_(4),which is attributed to its higher configuration entropy.Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material,enabling it as a promising cathode for SOFCs.
基金supported by National Natural Science Foundation of China under Grant Nos.52234009 and 52274383Partial financial support came from the Fundamental Research Funds for the Central Universities,JLU,Program for JLU Science and Technology Innovative Research Team(JLUSTIRT,2017TD-09)Program for the Central University Youth Innovation Team.
文摘A novel core-shell structured Al_(8)Mn_(4)Y-Al_(2)Ca phase and controllable solute-segregation are elaborately designed in dilute Mg-0.6Al-0.5Mn-0.1Ca-0.1Y alloy(wt.%),via incomplete peritectic transformation during twin-roll casting.When soaked in 3.5 wt.%NaCl solution,Al_(2)Ca shell with a low electrochemical potential prevents direct contact of noble Al_(8)Mn_(4)Y with Mg matrix,mitigating the micro-galvanic corrosion and meanwhile accelerating the formation of uniform corrosion film.Thereafter,solute(Al,Ca)-segregation motivates the formation of heterogeneous multilayered corrosion product films,enhancing corrosion resistance and even achieving self-healing upon long-term corrosion.Notably,the dilute Mg alloy exhibits a corrosion rate as low as 0.22±0.05 mm·y^(−1).
基金funded by the National Natural Science Foundation of China(NSFC)(Grant No.U1860111)Weifang Science and Technology Development Plan Project(Project No.2023ZJ1166).
文摘The crankshaft is subjected to complex rotational centrifugal force,periodic gas inertia force,and reciprocating inertia force during its working process.Consequently,the homogeneity requirement for crankshaft steel is exceptionally high.The distribution characteristics of center segregation and spot segregation of continuous casting bloom 42CrMoA crankshaft steel were analyzed by experiments,and the control mechanism of spot segregation by soft reduction zone and reduction amount was discussed.When the center solid fraction is between 0.61 and 1.00,an 8-mm soft reduction has a negligible impact on the flow of liquid steel at the end of solidification.Although it effectively improves center segregation,the improvement of spot segregation is limited.On the other hand,when the center solid fraction is between 0.31 and 1.00,a reduction of 10–12 mm,along with an expanded reduction zone and increased reduction amount,significantly promotes the flow of liquid steel at the end of solidification,reduces the size of equiaxed grains,mitigates the center negative segregation,and decreases the maximum size of spot segregation from 2954.29 to 1354.07μm.The number of spot segregations and the solutes enrichment degree of C,Cr,and Mn have also been significantly improved.An appropriate soft reduction zone and reduction amount can markedly ameliorate the semi-macro spot segregation of crankshaft steel blooms,thereby providing high-quality raw materials for subsequent products and enhancing the competitiveness of crankshaft products.
基金support from the National Key R&D Program of China(No.2021YFB3702403).
文摘The microstructure and mechanical properties of the compact strip production(CSP)processed quenching and partitioning(Q&P)steels were investigated through experimental methods to address the challenge of designing high-performance Q&P steels.Compared with the conventional process(CP)produced samples,with slightly reduced strength,the total elongation of the CSP produced samples was increased by nearly 7%.Microstructural analysis revealed that variations in austenite stability were not the primary cause for the differences in mechanical properties between the CSP and the CP.The CSP processed Q&P steel exhibited milder center segregation behavior in contrast to the CP processed Q&P steel.Consequently,in the CSP processed Q&P steel,a higher proportion of austenite and a lower proportion of martensite were observed at the center position,delaying the crack initiation in the central region and contributing to the enhanced ductility.The investigation into the CSP process reveals its effect on alleviation of segregation and enhancement of mechanical properties of the Q&P steel.
基金support for this research provided by the High-end Foreign Experts Recruitment Plan of China(Grant No.G2022105011L).
文摘The elemental segregation,microstructure,and mechanical properties of thermo-mechanical control process(TMCP)treated high-manganese wear-resistant steel(HMWS)were experimentally investigated.Firstly,the initial elemental segregation in the continuous casting slab of HMWS was characterized using the original position analysis.The results showed that the elemental segregation predominantly occurred near the quarter and the center regions of the slab.The homogenization of manganese(Mn)in the slab was not as obvious as that of other elements after the heating process.Subsequently,a series of hot-rolling tests were carried out on HMWS slab samples under different TMCP conditions,and the elemental segregation and microstructure of the TMCP-treated HMWS were investigated by microscopic analysis methods.The findings demonstrated that the segregations of carbon and silicon were effectively eliminated after the TMCP treatment,while Mn segregation presented a band-shaped arrangement and could be reduced at lower finishing rolling temperatures.The matrix phase of HMWS remained austenite regardless of the TMCP conditions,and the average size of austenite grains increased with the increasing finishing rolling temperature.Carbide particles were observed to form within austenite grains and even along grain boundaries at higher coiling temperatures.Finally,the mechanical tests were performed on the TMCP-treated HMWS at room temperature.The mechanical properties including tensile stress,yield stress,Charpy impact energy,and microhardness were discussed considering the effects of Mn segregation band,microstructure,and carbide precipitation.
基金financially supported by the National Natural Science Foundation of China(No.51675092)the Natural Science Foundation of Hebei Province,China(Nos.E2022501001,E2022501006).
文摘The effect of high pressure on the microstructure and microsegregation of Mg-11Al(mass fraction,%)alloys was studied through experiments and first-principles calculations.The results show that the Al content in the initial solid phase is high owing to the high solute partition coefficient and the large undercooling in the alloys solidified under pressures of 4-6 GPa,and the Al content in the initial solid phase increases with the increase of pressure.Consequently,the total amount of excess solute in the liquid phase in the final solidification stage decreases with increasing pressure,thus decreasing or suppressing the eutectic transformation.Furthermore,the microstructure of the alloys solidified under pressures of 5-6 GPa is a fine-grained solid solution,consisting of grains with high solubility of Al atoms and grain boundaries with abundant Al solutes.As the pressure increases,the grain boundary doping energy of Al atoms decreases,while their grain boundary segregation energy of Al atoms increases,and the charge density between the Mg-Al(Mg)bonds also rises.Therefore,the stability of the microstructure is improved,and the bond strength of grain boundaries is enhanced.
基金support provided by the National Natural Science Foundation of China(No.52174357)Fundamental Research Funds for the Central Universities(No.DUT21LAB132)The Basic and Applied Basic Research Major Programme of Guangdong Province,China(No.2021B0301030003)。
文摘This study investigates the impact of Zn alloying on the dispersion of the reinforcing particle in Mg_(2)Sn/Mg composites.In the composite,Zn manifests in three distinct forms:Zn segregation layer between Mg–Mg_(2)Sn,the solid solution and the MgZn_(2)phase.First-principles calculations confirm that the formation of Zn segregation layer decreases the interfacial energy of the Mg–Mg_(2)Sn.Importantly,this segregation layer significantly enhances the comigration capability of Mg_(2)Sn particles with Mg matrix during sintering flow,effectively hindering the agglomeration and coarsening of the nano-sized reinforcing phase.The dense and uniformly distributed nano-sized Mg_(2)Sn significantly increases the activity of non-basal slip,ensuring good elongation of the composite while enhancing strength.It can be concluded that enhancing the comigration-ability of reinforcing particles with the matrix is an effective strategy for achieving controlled dispersion of high-volume reinforcing particles and an excellent combination of strength and ductility in magnesium matrix composites.
基金funded by the National Natural Science Foundation of China(Nos.52130404 and 52304121)the Fundamental Research Funds for the Central Universities,China(No.FRF-TP-22-112A1).
文摘Utilizing coarse aggregates containing mining waste rock for backfilling addresses the strength requirements and reduces the expenses associated with binder and solid waste treatment.However,this type of material is prone to aggregate segregation,which can lead to uneven deformation and damage to the backfill.We employed an image-segmentation method that incorporated machine learning to analyze the distribution information of the aggregates on the splitting surface of the test blocks.The results revealed a nonlinear rela-tionship between aggregate segregation and variations in solid concentration(SC)and cement/aggregate ratio(C/A).The SC of 81wt%-82wt%and C/A of 10.00wt%-12.50wt%reflect surges in fluid dynamics,friction effects,and shifts in their dominance.A uniaxial compression experiment,supplemented with additional strain gauges and digital image correlation technology,enabled us to analyze the mechanical properties and failure mechanism under the influence of aggregate segregation.It was found that the uniaxial compressive strength,ranging from 1.75 MPa to 12.65 MPa,is linearly related to both the SC and C/A,and exhibits no significant relation-ship with the degree of segregation in numerical terms.However,the degree of segregation affects the development trend of the elastic modulus to a certain extent,and a standard deviation of the aggregate area ratio of less than 1.63 clearly indicates a higher elastic modu-lus.In the pouring direction,the top area of the test block tended to form a macroscopic fracture surface earlier.By contrast,the compressibility of the bottom area was greater than that of the top area.The intensification of aggregate segregation widened the differences in the deformation and failure characteristics between the different areas.For samples with different uniformities,significant differences in local deformation ranging from 515.00μεto 1693.70μεwere observed during the stable deformation stage.The extreme unevenness of the aggregate leads to rapid crack penetration in the sample,causing macroscopic tensile failure and resulting in premature structural failure.
基金supported by PRISMS(PRedictive Integrated Structural Materials Science)center which is located at University of Michigan and funded by U.S.Department of Energy,Office of Basic Energy Science,Division of Materials Science and Engineering(Grant award number DE-SC0008637)support from Michigan Center for Materials Characterization(MC2)at University of Michigan and Canmet MATERIALS,Natural Resources Canada+1 种基金the Extreme Science and Engineering Discovery Environment(XSEDE)Stampede2 at the TACC through allocation TG-MSS160003the National Energy Research Scientific Computing Center(NERSC),a U.S.Department of Energy Office of Science User Facility operated under Contract No.DE-AC02-05CH11231。
文摘As a rare earth solute element in Mg alloys,Y has the beneficial effects of increasing both the strength and the ductility as well as weakening the crystallographic texture.To achieve a more fundamental understanding on how Y addition affects the microstructural evolution and mechanical properties,the Y segregation behavior at grain boundaries was investigated in Mg-1wt.%Y and Mg-7wt.%Y alloys at different conditions.The segregation intensity and its dependence on the grain boundary misorientation angle were experimentally characterized and computationally predicted.Strong segregation at grain boundaries was observed in both low and high Y-containing alloys.Y segregation was found to remain in alloy Mg-7Y after high-temperature annealing heat treatment at 540℃.No direct correlation between the Y segregation intensity and the grain boundary misorientation angle could be established based on either the experimental characterization or the atomistic simulation with a spectral model.We thus conclude that grain boundary segregation of Y is independent of grain boundary misorientation angle.
基金Project supported by the National Natural Science Foundation of China(52301041)Guizhou Provincial Science and Technology Projects(Qingnian No.2024-123)the Special Fund for Special Posts of Guizhou University(2023-26,2023-53)。
文摘In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Zn atoms along both high and lowangle grain boundaries(GBs).As compared with as-rolled plate,the yield strength,ultimate tensile strength,and the elongation of annealed sample is increased by 15.6%,14%,and 8.4%,respectively,acquiring an obvious strength-ductility synergy effect.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects including dislocation annihilation and grain coarsening.Meanwhile,the directional migration of Zn atoms and the annihilation of dislocations provide a"clear"space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.
基金supported by the National Natural Science Foundation of China(No.52225101)the Fundamental Research Funds for the Central Universities(2023CDJYXTD-002)+1 种基金supported by the Special Fund for Special Posts of Guizhou University(No.202353)Guizhou Provincial Basic Research Program(Natural Science)(Qingnian Yindao No.2024-123).
文摘Interface segregation of solute atoms has a profound effect on properties of engineering alloys.In this study,we report a novel strategy for breaking the strength-ductility dilemma of Mg alloy via solute segregation.The hot extruded Mg-1.8Gd-0.3Zr(wt.%)alloy sheet was subjected to three different passes of rolling,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Gd atoms along high and low-angel grain boundaries(GBs).Under almost precipitation-free conditions,the strength and ductility of rolled alloy sheets are simultaneously improved after annealing.Especially for the annealed 3-passes-rolled specimen,the yield strength,ultimate tensile strength,and elongation are simultaneously increased by 11.2%,7.3%,and 18%,respectively.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects,including dislocation annihilation and grain coarsening during the heating.Meanwhile,the directional migration of Gd atoms and the annihilation of dislocations provide a“clear”space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.
基金supported financially by the National Key R&D Program of China(Grant No.2023YFE0111500)the National Natural Science Foundation of China(Grant Nos.52321006,T2394480,T2394484,22109143,22475196,22479131)+11 种基金the Research Grants Council of Hong Kong(CRF C4005-22YRGC Senior Research Fellowship Scheme(SRFS2223-5S01))the Joint Fund for Provincial Science and Technology R&D Program of Henan(grant no.242301420051)the Opening Project of the State Key Laboratory of Advanced Technology for Float Glass(grant no.2022KF04)the China Postdoctoral Innovative Talent Support Program(grant no.BX2021271)the China Postdoctoral Science Foundation(grant no.2022M712851)the Graduate Education Reform Project of Henan Province(Grant No.2023SJGLX136Y)the Key R&D Special Program of Henan Province(Grant No.241111242000)the Program for Science&Technology Innovation Talents in Universities of Henan Province(Grant No.25HASTIT005)the Training Plan for Young Backbone Teachers of Zhengzhou University(Grant No.2023ZDGGJS017)the Joint Research Project of Puyang ShengtongJuyuan New Materials Co.Ltd.(Grant No.20230128A)。
文摘Wide-bandgap mixed-halide perovskites,particularly CsPbIBr_(2),hold great promise for multi-junction solar cells due to their well-matched bandgap and all-inorganic material system.However,their inherent susceptibility to light-induced phase segregation(LIPS)limits efficiency and stability.In this work,we investigate the effect of three organic additives-4-cyclopentene-1,3-dione(CPD),maleimide(HPD),and 3,4-dibromo-1H-pyrrole-2,5(2H,5H)-dione(BrPD)-on LIPS in wide-bandgap CsPbIBr_(2)perovskite films.The additives form various chemical interactions,including coordination bonds,hydrogen bonds,and ionic bonds,with I^(-)and undercoordinated Pb^(2+)ions,among which BrPD has the strongest interaction.This interaction regulates crystallization and improves film morphology.The BrPD-modified films have the largest grain size and the highest light stability,suppressing LIPS,enhancing carrier transfer,and improving device performance.BrPD-modified CsPbIBr_(2)-based solar cells achieve a power conversion efficiency(PCE)of 11.34%,outperforming the control(8.96%)and other additives.Moreover,BrPDmodified devices show excellent stability,retaining 94%of their initial PCE after 60 min of continuous light exposure.This work highlights the potential of strategically selected organic additives to enhance the stability and performance of perovskite solar cells,offering valuable insights for the design of high-efficiency and long-lasting perovskite-based optoelectronic devices.
基金Z.X.and T.A.S.acknowledge the financial support by the German Research Foundation(DFG)(Grant Nr.505716422)T.A.S.are grateful for the financial support from the DFG(Grant Nr.AL1343/7-1,AL1343/8-1 and Yi 103/3-1)+4 种基金Z.X.,S.K.K.and U.K.acknowledge financial support by the DFG through the projects A05,A07 and C02 of the SFB1394 StructuralChemical Atomic Complexity-From Defect Phase Diagrams to Material Properties,project ID 409476157Additionally,Z.X.and S.K.K.are grateful for funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(grant agreement No.852096 FunBlocks)J.G.acknowledges funding from the French National Research Agency(ANR),Grant ANR-21-CE08-0001(ATOUUM)and ANR-22-CE92-0058-01(SILA)The authors gratefully acknowledge the computing time provided to them at the NHR Center NHR4CES at RWTH Aachen University(project number p0020431 and p0020267)。
文摘Grain boundary(GB)segregation substantially influences the mechanical properties and performance of magnesium(Mg).Atomic-scale modeling,typically using ab-initio or semi-empirical approaches,has mainly focused on GB segregation at highly symmetric GBs in Mg alloys,often failing to capture the diversity of local atomic environments and segregation energies,resulting in inaccurate structure-property predictions.This study employs atomistic simulations and machine learning models to systematically investigate the segregation behavior of common solute elements in polycrystalline Mg at both 0 K and finite temperatures.The machine learning models accurately predict segregation thermodynamics by incorporating energetic and structural descriptors.We found that segregation energy and vibrational free energy follow skew-normal distributions,with hydrostatic stress,an indicator of excess free volume,emerging as an important factor influencing segregation tendency.The local atomic environment's flexibility,quantified by flexibility volume,is also crucial in predicting GB segregation.Comparing the grain boundary solute concentrations calculated via the Langmuir-Mc Lean isotherm with experimental data,we identified a pronounced segregation tendency for Nd,highlighting its potential for GB engineering in Mg alloys.This work demonstrates the powerful synergy of atomistic simulations and machine learning,paving the way for designing advanced lightweight Mg alloys with tailored properties.
