The article considers a relaxation of the water/polypropylene glycol-425 solution with a lower critical solution temperature(LCST)following its pulsed superheating concerning liquid-liquid and liquid-vapor equilibrium...The article considers a relaxation of the water/polypropylene glycol-425 solution with a lower critical solution temperature(LCST)following its pulsed superheating concerning liquid-liquid and liquid-vapor equilibrium lines,as well as the liquid-liquid spinodal.Superheating was performed using the pulsed heat generation method in a micro-sized wire probe.The main heating mode was the constant(over the pulse length)power mode.Characteristic heating rates ranged from 0.05×10^(5) to 2×10^(5) K/s,while the degree of superheating concerning the spinodal was up to 200 K.The temperature of spontaneous boiling-up and the amplitude of the corresponding signal were monitored as functions of the heating rate set by the power value.The results demonstrate an example of the interaction of liquidliquid and liquid-vapor phase transitions,as well as the spinodal decomposition of a solution with LCST against the background of its unstable states.We proposed a physical model to explain the minimum spontaneous boiling-up temperature revealed within a certain range of heating rates,which is not typical of completely miscible solutions.Further research will focus on establishing a general criterion for the possibility of spinodal decomposition of such solutions under the conditions of rapid heating.展开更多
Ensuring the long-term and stable operation of mechanical equipment has been a research emphasis with the development of aerospace and polar exploration,which necessitates the prepared materials with high mechanical s...Ensuring the long-term and stable operation of mechanical equipment has been a research emphasis with the development of aerospace and polar exploration,which necessitates the prepared materials with high mechanical strength as well as excellent wear resistance[1].The traditional lubricant is widely acknowledged to be susceptible to evaporation or decomposition under extreme conditions,necessitating the deposition of a protective thin film on critical mechanical parts’surfaces to enhance their mechanical and tribological properties[2,3].展开更多
High entropy alloys(HEAs)constituted of single solid solution phase,but remains chemical inhomogeneity in nature due to its multi-principal composition.Currently,existence of nanoscale spinodal decomposition(SD)phase ...High entropy alloys(HEAs)constituted of single solid solution phase,but remains chemical inhomogeneity in nature due to its multi-principal composition.Currently,existence of nanoscale spinodal decomposition(SD)phase in matrix was found to have significant impact on the properties of HEAs.Nevertheless,the morphology evolution and the kinetics of SD is not clear,which hinders in-depth understanding of the structure-property relationship.In this study,we examine the spinodal structures in(FeCoCrNi)85(AlCu)15 HEAs at different states using in-situ small-angle neutron scattering(SANS),in conjunction with transmission electron microscopy technique.The result demonstrates that SD occurred when aging the HEA samples at temperatures ranging from 500 to 800℃,which leads to the phase constitution of NiAlCu-rich and FeCoCr-rich spinodal phases,L1_(2)ordered phases,and FCC matrix.The characteristic wavelength of SD(λ_(SD))grows from 5.31 to 51.26 nm when aging temperature rises from 500 to 800℃,which explains the enhancement of the alloy’s microhardness.The SD kinetics was unraveled by fitting the time-dependentλ_(SD)through in-situ SANS measurement at 700℃.During isothermal treatment at 700℃,theλ_(SD)increases from 10.42 to 17.43 nm with prolonged time,and SD is in the late stage from the exponential trend of theλ_(SD)over time.Moreover,comparing with aging temperature,the aging time has a relatively minor impact on the coarsening of SD.展开更多
To study the formation and transformation mechanism of long-period stacked ordered(LPSO)structures,a systematic atomic scale analysis was conducted for the structural evolution of long-period stacked ordered(LPSO)stru...To study the formation and transformation mechanism of long-period stacked ordered(LPSO)structures,a systematic atomic scale analysis was conducted for the structural evolution of long-period stacked ordered(LPSO)structures in the Mg-Gd-Y-Zn-Zr alloy annealed at 300℃~500℃.Various types of metastable LPSO building block clusters were found to exist in alloy structures at different temperatures,which precipitate during the solidification and homogenization process.The stability of Zn/Y clusters is explained by the first principles of density functional theory.The LPSO structure is distinguished by the arrangement of its different Zn/Y enriched LPSO structural units,which comprises local fcc stacking sequences upon a tightly packed plane.The presence of solute atoms causes local lattice distortion,thereby enabling the rearrangement of Mg atoms in the different configurations in the local lattice,and local HCP-FCC transitions occur between Mg and Zn atoms occupying the nearest neighbor positions.This finding indicates that LPSO structures can generate necessary Schockley partial dislocations on specific slip surfaces,providing direct evidence of the transition from 18R to 14H.Growth of the LPSO,devoid of any defects and non-coherent interfaces,was observed separately from other precipitated phases.As a result,the precipitation sequence of LPSO in the solidification stage was as follows:Zn/Ycluster+Mg layers→various metastable LPSO building block clusters→18R/24R LPSO;whereas the precipitation sequence of LPSO during homogenization treatment was observed to be as follows:18R LPSO→various metastable LPSO building block clusters→14H LPSO.Of these,14H LPSO was found to be the most thermodynamically stable structure.展开更多
The chemical boundaries inside the ultrafine spinodal decomposition structure in metastable β-Ti alloys can act as a new feature to architect heterogeneous microstructures.In this work,we combined two semi-empirical ...The chemical boundaries inside the ultrafine spinodal decomposition structure in metastable β-Ti alloys can act as a new feature to architect heterogeneous microstructures.In this work,we combined two semi-empirical methods,i.e.,the d-electron theory and the e/a electron concentration,to achieve the spinodal decomposition structure in a metastable β Ti-4.5Al-4.5Mo-7V-1.5Cr-1.5Zr(wt.%)alloy.Utilizing the spinodal decomposition structure,the aged Ti-Al-Mo-V-Cr-Zr alloys showed multi-architectured α precipitates spanning from micron-scale(primary α_(p))to nano-scale(secondary α_(s))that were uniformly distributed in the β-domains.Being compared with the forged sample,the multi-scale heterogeneous microstructure enables the aged β-Ti alloy to have ultra-high strength(yield strength ~1366 MPa and ultimate tensile strength ~1424 MPa)and an appreciable ductility(~9.3%).Strengthening models were proposed for the present alloys to estimate the contribution of various microstructural features to the measured yield strength.While the solid solution strengthening,β-spinodal strengthening,and back stress strengthening made comparable contributions to the strength of the forged alloy,the back stress strengthening was the predominant strengthening effect in the aged alloy.This alloy design approach based on chemical boundary engineering to construct multi-architectured α precipitates provided an effective strategy for achieving an outstanding combination of ultra-high strength and ductility in metastable β-Ti alloys.展开更多
The spinodal decomposition method emerges as a promising methodology,showcasing its potential in exploring the design space for metamaterial structures.However,spinodal structures design is still largely limited to re...The spinodal decomposition method emerges as a promising methodology,showcasing its potential in exploring the design space for metamaterial structures.However,spinodal structures design is still largely limited to regular structures,due to their relatively easy parameterization and controllability.Efficiently predicting the mechanical properties of 3D spinodal membrane structure remains a challenge,given that the features of the membrane necessitate adaptive mesh through the modelling process.This paper proposes an integrated approach for morphological design with customized mechanical properties,incorporating the spinodal decomposition method and adaptive coarse-grained modeling,which can produce various morphologies such as lamellar,columnar,and cubic structures.Pseudo-periodic parameterβand orientational parameterΘ(θ_(1),θ_(2),θ_(3))are identified to achieve the optimal goal of anisotropic mechanical properties.Parametric analysis is conducted to reveal the correlation between the customized spinodal structure and mechanical performance.Our work provides an integrated approach for morphological variation and tuning mechanical properties,paving the way for the design and development of customized functional materials similar to 3D spinodal membrane structures.展开更多
基金the expense of a grant of the Russian Science Foundation(project No.23-69-10006),https://rscf.ru/project/23-69-10006/(accessed on 6 May 2025).
文摘The article considers a relaxation of the water/polypropylene glycol-425 solution with a lower critical solution temperature(LCST)following its pulsed superheating concerning liquid-liquid and liquid-vapor equilibrium lines,as well as the liquid-liquid spinodal.Superheating was performed using the pulsed heat generation method in a micro-sized wire probe.The main heating mode was the constant(over the pulse length)power mode.Characteristic heating rates ranged from 0.05×10^(5) to 2×10^(5) K/s,while the degree of superheating concerning the spinodal was up to 200 K.The temperature of spontaneous boiling-up and the amplitude of the corresponding signal were monitored as functions of the heating rate set by the power value.The results demonstrate an example of the interaction of liquidliquid and liquid-vapor phase transitions,as well as the spinodal decomposition of a solution with LCST against the background of its unstable states.We proposed a physical model to explain the minimum spontaneous boiling-up temperature revealed within a certain range of heating rates,which is not typical of completely miscible solutions.Further research will focus on establishing a general criterion for the possibility of spinodal decomposition of such solutions under the conditions of rapid heating.
基金the National Natural Science Foundation of China(No.52175188)the Key Research and De-velopment Program of Shaanxi Province(No.2023-YBGY-434)+2 种基金the Open Fund of Liaoning Provincial Key Laboratory of Aero-engine Materials Tribology(No.LKLAMTF202301)the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012378)the Science and Technology on Reactor System Design Tech-nology Laboratory and the Fundamental Research Funds for the Central Universities.
文摘Ensuring the long-term and stable operation of mechanical equipment has been a research emphasis with the development of aerospace and polar exploration,which necessitates the prepared materials with high mechanical strength as well as excellent wear resistance[1].The traditional lubricant is widely acknowledged to be susceptible to evaporation or decomposition under extreme conditions,necessitating the deposition of a protective thin film on critical mechanical parts’surfaces to enhance their mechanical and tribological properties[2,3].
基金financially supported by the National Key Research and Development Program of China(Grant No.2021YFA1600701)the Guangdong Basic and Applied Basic Research Foundation,China(Project No.2021B1515140028)the National Natural Science Foundation of China(Grant No.12275154)。
文摘High entropy alloys(HEAs)constituted of single solid solution phase,but remains chemical inhomogeneity in nature due to its multi-principal composition.Currently,existence of nanoscale spinodal decomposition(SD)phase in matrix was found to have significant impact on the properties of HEAs.Nevertheless,the morphology evolution and the kinetics of SD is not clear,which hinders in-depth understanding of the structure-property relationship.In this study,we examine the spinodal structures in(FeCoCrNi)85(AlCu)15 HEAs at different states using in-situ small-angle neutron scattering(SANS),in conjunction with transmission electron microscopy technique.The result demonstrates that SD occurred when aging the HEA samples at temperatures ranging from 500 to 800℃,which leads to the phase constitution of NiAlCu-rich and FeCoCr-rich spinodal phases,L1_(2)ordered phases,and FCC matrix.The characteristic wavelength of SD(λ_(SD))grows from 5.31 to 51.26 nm when aging temperature rises from 500 to 800℃,which explains the enhancement of the alloy’s microhardness.The SD kinetics was unraveled by fitting the time-dependentλ_(SD)through in-situ SANS measurement at 700℃.During isothermal treatment at 700℃,theλ_(SD)increases from 10.42 to 17.43 nm with prolonged time,and SD is in the late stage from the exponential trend of theλ_(SD)over time.Moreover,comparing with aging temperature,the aging time has a relatively minor impact on the coarsening of SD.
基金financially funded by Natural Science Basic Research Program of Shaanxi(grant number 2022JM-239)Key Research and Development Project of Shaanxi Provincial(grant number 2021LLRH-05–08)。
文摘To study the formation and transformation mechanism of long-period stacked ordered(LPSO)structures,a systematic atomic scale analysis was conducted for the structural evolution of long-period stacked ordered(LPSO)structures in the Mg-Gd-Y-Zn-Zr alloy annealed at 300℃~500℃.Various types of metastable LPSO building block clusters were found to exist in alloy structures at different temperatures,which precipitate during the solidification and homogenization process.The stability of Zn/Y clusters is explained by the first principles of density functional theory.The LPSO structure is distinguished by the arrangement of its different Zn/Y enriched LPSO structural units,which comprises local fcc stacking sequences upon a tightly packed plane.The presence of solute atoms causes local lattice distortion,thereby enabling the rearrangement of Mg atoms in the different configurations in the local lattice,and local HCP-FCC transitions occur between Mg and Zn atoms occupying the nearest neighbor positions.This finding indicates that LPSO structures can generate necessary Schockley partial dislocations on specific slip surfaces,providing direct evidence of the transition from 18R to 14H.Growth of the LPSO,devoid of any defects and non-coherent interfaces,was observed separately from other precipitated phases.As a result,the precipitation sequence of LPSO in the solidification stage was as follows:Zn/Ycluster+Mg layers→various metastable LPSO building block clusters→18R/24R LPSO;whereas the precipitation sequence of LPSO during homogenization treatment was observed to be as follows:18R LPSO→various metastable LPSO building block clusters→14H LPSO.Of these,14H LPSO was found to be the most thermodynamically stable structure.
基金supported by the National Natural Science Foundation of China(Grant Nos.92163201 and U2067219)Shaanxi Province Youth Innovation Team Project(No.22JP042)+1 种基金Shaanxi Province Innovation Team Project(No.2024RS-CXTD-58)the Fundamental Research Funds for the Central Universities(No.xtr022019004).
文摘The chemical boundaries inside the ultrafine spinodal decomposition structure in metastable β-Ti alloys can act as a new feature to architect heterogeneous microstructures.In this work,we combined two semi-empirical methods,i.e.,the d-electron theory and the e/a electron concentration,to achieve the spinodal decomposition structure in a metastable β Ti-4.5Al-4.5Mo-7V-1.5Cr-1.5Zr(wt.%)alloy.Utilizing the spinodal decomposition structure,the aged Ti-Al-Mo-V-Cr-Zr alloys showed multi-architectured α precipitates spanning from micron-scale(primary α_(p))to nano-scale(secondary α_(s))that were uniformly distributed in the β-domains.Being compared with the forged sample,the multi-scale heterogeneous microstructure enables the aged β-Ti alloy to have ultra-high strength(yield strength ~1366 MPa and ultimate tensile strength ~1424 MPa)and an appreciable ductility(~9.3%).Strengthening models were proposed for the present alloys to estimate the contribution of various microstructural features to the measured yield strength.While the solid solution strengthening,β-spinodal strengthening,and back stress strengthening made comparable contributions to the strength of the forged alloy,the back stress strengthening was the predominant strengthening effect in the aged alloy.This alloy design approach based on chemical boundary engineering to construct multi-architectured α precipitates provided an effective strategy for achieving an outstanding combination of ultra-high strength and ductility in metastable β-Ti alloys.
基金supported by the National Natural Science Foundation of China(Grant No.11872278)the Science and Technology Commission of Shanghai Municipality(Grant No.21ZR1467200)the Fundamental Research Funds for the Central Universities.
文摘The spinodal decomposition method emerges as a promising methodology,showcasing its potential in exploring the design space for metamaterial structures.However,spinodal structures design is still largely limited to regular structures,due to their relatively easy parameterization and controllability.Efficiently predicting the mechanical properties of 3D spinodal membrane structure remains a challenge,given that the features of the membrane necessitate adaptive mesh through the modelling process.This paper proposes an integrated approach for morphological design with customized mechanical properties,incorporating the spinodal decomposition method and adaptive coarse-grained modeling,which can produce various morphologies such as lamellar,columnar,and cubic structures.Pseudo-periodic parameterβand orientational parameterΘ(θ_(1),θ_(2),θ_(3))are identified to achieve the optimal goal of anisotropic mechanical properties.Parametric analysis is conducted to reveal the correlation between the customized spinodal structure and mechanical performance.Our work provides an integrated approach for morphological variation and tuning mechanical properties,paving the way for the design and development of customized functional materials similar to 3D spinodal membrane structures.
