This study used the pseudo-spinodal mechanism to obtain the ultrafineαphase for designing highstrength titanium alloy.Diffusion multiple experiments were designed to find the composition range of TM-x Mo-y V alloy(TM...This study used the pseudo-spinodal mechanism to obtain the ultrafineαphase for designing highstrength titanium alloy.Diffusion multiple experiments were designed to find the composition range of TM-x Mo-y V alloy(TM:Ti-4.5 Al-2 Cr-2.5 Nb-2 Zr-1 Sn)for obtaining ultrafineαphase.CALPHAD results confirm that when the alloy composition is located near the intersection of theαandβphase free energy curves,the alloy will undergo pseudo-spinodal transformation and obtain the ultrafineαphase.The designed TM-6 Mo-3 V alloy has a yield strength of 1411 MPa and an elongation of 6.5%.The strength of the alloy depends on the thickness,fraction of theαphase and the solid solution strengthening effect of the alloying elements.The deformation mechanism of the alloy is the dislocation slip of theαandβphases and the twin deformation of theαphase.The large number ofα/βinterfaces produced by the fineαphase is the main reason for limiting the ductility of the alloy.The use of the pseudo-spinodal mechanism combined with diffusion multiple experiments and CALPHAD is an effective method for designing high-strength titanium alloys.展开更多
On purpose of studying the sluggish diffusion of high-entropy alloys, three different face centered cubic Co-Cr-Cu-Fe-Ni high-entropy alloys were prepared, and assembled into three groups of sandwich- type diffusion m...On purpose of studying the sluggish diffusion of high-entropy alloys, three different face centered cubic Co-Cr-Cu-Fe-Ni high-entropy alloys were prepared, and assembled into three groups of sandwich- type diffusion multiple annealed at 1273, 1323, and 1373 K respectively. By means of the electron probe microanalyzer technique and recently developed numerical inverse method, the composition- dependent interdiffusivities at different temperatures were effectively evaluated by minimizing the residual between the model-predicted compositions/interdiffusion fluxes and the respectively experi- mental ones. After that, the tracer diffusivities were predicted based on the assessed mobility parameters and thermodynamic descriptions with the simplified ideal solution model. The comprehensive compari- son between the interdiffusivities/tracer diffusivities in the Co-Cr-Cu-Fe-Ni high-entropy alloys and those in sub-binary, ternary, quaternary and other quinary alloys indicates that the sluggish diffusion exists in interdiffusion instead of tracer diffusion for the present Co-Cr-Cu-Fe-Ni high-entropy alloys.展开更多
Multiple fractured horizontal well(MFHW) is widely applied in the development of shale gas. To investigate the gas flow characteristics in shale, based on a new dual mechanism triple continuum model, an analytical sol...Multiple fractured horizontal well(MFHW) is widely applied in the development of shale gas. To investigate the gas flow characteristics in shale, based on a new dual mechanism triple continuum model, an analytical solution for MFHW surrounded by stimulated reservoir volume(SRV) was presented. Pressure and pressure derivative curves were used to identify the characteristics of flow regimes in shale. Blasingame type curves were established to evaluate the effects of sensitive parameters on rate decline curves, which indicates that the whole flow regimes could be divided into transient flow, feeding flow, and pseudo steady state flow. In feeding flow regime, the production of gas well is gradually fed by adsorbed gases in sub matrix, and free gases in matrix. The proportion of different gas sources to well production is determined by such parameters as storability ratios of triple continuum, transmissibility coefficients controlled by dual flow mechanism and fracture conductivity.展开更多
A combinatorial approach was applied to investigating the influence of Fe content on the microstructures and properties of Ti6Al4V alloy.A diffusion couple was manufactured with Ti6Al4V and Ti6Al4V20Fe alloys and anne...A combinatorial approach was applied to investigating the influence of Fe content on the microstructures and properties of Ti6Al4V alloy.A diffusion couple was manufactured with Ti6Al4V and Ti6Al4V20Fe alloys and annealed at 1000°C for 600 h to obtain a wide range of compositions.By combining electron probe micro-analysis(EPMA),scanning electron microscopy(SEM)and nanoindentation,the relationships between composition and microstructure as well as hardness were determined.It is found that after aging the Ti6Al4V5Fe sample contains reasonable(about 55%)volume fraction of fineαphase and shows the peak hardness among the Ti6Al4VxFe alloys.Therefore,it is a promising candidate for the development of titanium alloys.HAADF-STEM and XRD reveal that after quenching from the singleβphase field,the metastableα''lamellae form in the Ti6Al4V5Fe alloy,and on subsequent isothermal aging,theα''lamellae become coarse and act as precursors/preferential nucleation sites for the stableαphase.展开更多
Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and...Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.展开更多
There are several diffusion processes with different temperatures in modern semiconductor technology.The impurity distribution after these diffusion processes is analyzed and a simple expression for describing the dis...There are several diffusion processes with different temperatures in modern semiconductor technology.The impurity distribution after these diffusion processes is analyzed and a simple expression for describing the distribution is given.It is found that the impurity distribution after multiple diffusion processes can be characterized with an effective diffusion length.The relation between this effective diffusion length and the diffusion lengths of each diffusion process is given and shows itself to be very simple and instructive.The results of the expression agree well with numerical simulations by using SUPREMⅣ.An example of the application of the expression is also shown.展开更多
The influence of Nb,Co,Ti,and Al on the microstructural evolution and mechanical properties of GH4061 superalloy was simultaneously investigated using diffusion multiple techniques combined with double aging heat trea...The influence of Nb,Co,Ti,and Al on the microstructural evolution and mechanical properties of GH4061 superalloy was simultaneously investigated using diffusion multiple techniques combined with double aging heat treatment.Co exhibited the highest penetration depth with monotonic concentration decrease,significantly inhibiting the formation of needle-likeδphase and reduced the precipitation size of theγ′phase.Nb diffusion formed distinct layers with clear interfaces,promoting substantialγ′′phase precipitation,while simultaneously enhancing hardness through solid solution strengthening.Ti and Al diffusion generated substantial diffusion layers containing Ti-Ni enriched needle-likeηphases and enhancedγ′phase growth,characterized by increased size and volume fraction compared to the base alloy.In contrast to the base alloy,this diffusion layer was devoid of phases enriched with Nb.Mechanical property analysis demonstrated that high concentrations of Nb,Al,and Ti enhanced alloy hardness through various strengthening mechanisms,whereas increased Co content diminished the size of theγ′phase at the interface,resulting in reduced hardness.This high-throughput experimental approach significantly reduced experimental workload while enabling detailed analysis of varying element concentrations on microstructure and properties.展开更多
基金the National Key Technologies R&D Program of China(Nos.2018YFB0704100 and 2016YFB0701301)the National Natural Science Foundation of China(Nos.51901251 and 51671218)the Natural Science Foundation of Hunan Province China(No.2020JJ5750)。
文摘This study used the pseudo-spinodal mechanism to obtain the ultrafineαphase for designing highstrength titanium alloy.Diffusion multiple experiments were designed to find the composition range of TM-x Mo-y V alloy(TM:Ti-4.5 Al-2 Cr-2.5 Nb-2 Zr-1 Sn)for obtaining ultrafineαphase.CALPHAD results confirm that when the alloy composition is located near the intersection of theαandβphase free energy curves,the alloy will undergo pseudo-spinodal transformation and obtain the ultrafineαphase.The designed TM-6 Mo-3 V alloy has a yield strength of 1411 MPa and an elongation of 6.5%.The strength of the alloy depends on the thickness,fraction of theαphase and the solid solution strengthening effect of the alloying elements.The deformation mechanism of the alloy is the dislocation slip of theαandβphases and the twin deformation of theαphase.The large number ofα/βinterfaces produced by the fineαphase is the main reason for limiting the ductility of the alloy.The use of the pseudo-spinodal mechanism combined with diffusion multiple experiments and CALPHAD is an effective method for designing high-strength titanium alloys.
基金financially supported by the National Natural Science Foundation of China(Grant No.51474239)the National Key Research and Development Program of China(Grant No.2016YFB0301101)+1 种基金financial support from the Huxiang Youth Talent Plan released by Hunan Province,Chinathe project supported by State Key Laboratory of Powder Metallurgy Foundation,Central South University,Changsha,China
文摘On purpose of studying the sluggish diffusion of high-entropy alloys, three different face centered cubic Co-Cr-Cu-Fe-Ni high-entropy alloys were prepared, and assembled into three groups of sandwich- type diffusion multiple annealed at 1273, 1323, and 1373 K respectively. By means of the electron probe microanalyzer technique and recently developed numerical inverse method, the composition- dependent interdiffusivities at different temperatures were effectively evaluated by minimizing the residual between the model-predicted compositions/interdiffusion fluxes and the respectively experi- mental ones. After that, the tracer diffusivities were predicted based on the assessed mobility parameters and thermodynamic descriptions with the simplified ideal solution model. The comprehensive compari- son between the interdiffusivities/tracer diffusivities in the Co-Cr-Cu-Fe-Ni high-entropy alloys and those in sub-binary, ternary, quaternary and other quinary alloys indicates that the sluggish diffusion exists in interdiffusion instead of tracer diffusion for the present Co-Cr-Cu-Fe-Ni high-entropy alloys.
基金Project(2011ZX05015)supported by Important National Science and Technology Specific Projects of the "Twelfth Five-years" Plan Period,China
文摘Multiple fractured horizontal well(MFHW) is widely applied in the development of shale gas. To investigate the gas flow characteristics in shale, based on a new dual mechanism triple continuum model, an analytical solution for MFHW surrounded by stimulated reservoir volume(SRV) was presented. Pressure and pressure derivative curves were used to identify the characteristics of flow regimes in shale. Blasingame type curves were established to evaluate the effects of sensitive parameters on rate decline curves, which indicates that the whole flow regimes could be divided into transient flow, feeding flow, and pseudo steady state flow. In feeding flow regime, the production of gas well is gradually fed by adsorbed gases in sub matrix, and free gases in matrix. The proportion of different gas sources to well production is determined by such parameters as storability ratios of triple continuum, transmissibility coefficients controlled by dual flow mechanism and fracture conductivity.
基金Project(2014CB644000)supported by the National Basic Research Program of ChinaProject(2016YFB0701301)supported by the National Key Technology R&D Program of China+1 种基金Projects(51371200,51671218)supported by the National Natural Science Foundation of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China
文摘A combinatorial approach was applied to investigating the influence of Fe content on the microstructures and properties of Ti6Al4V alloy.A diffusion couple was manufactured with Ti6Al4V and Ti6Al4V20Fe alloys and annealed at 1000°C for 600 h to obtain a wide range of compositions.By combining electron probe micro-analysis(EPMA),scanning electron microscopy(SEM)and nanoindentation,the relationships between composition and microstructure as well as hardness were determined.It is found that after aging the Ti6Al4V5Fe sample contains reasonable(about 55%)volume fraction of fineαphase and shows the peak hardness among the Ti6Al4VxFe alloys.Therefore,it is a promising candidate for the development of titanium alloys.HAADF-STEM and XRD reveal that after quenching from the singleβphase field,the metastableα''lamellae form in the Ti6Al4V5Fe alloy,and on subsequent isothermal aging,theα''lamellae become coarse and act as precursors/preferential nucleation sites for the stableαphase.
基金supported by National Science and Technology Major Project (J2019-IV-0003-0070)the Natural Science Foundation of China (91860105,52074366)+4 种基金China Postdoctoral Science Foundation (2019M662799)Natural Science Foundation of Hunan Province of China (2021JJ40757)the Science and Technology Innovation Program of Hunan Province (2021RC3131)Changsha Municipal Natural Science Foundation (kq2014126)Project Supported by State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.
文摘There are several diffusion processes with different temperatures in modern semiconductor technology.The impurity distribution after these diffusion processes is analyzed and a simple expression for describing the distribution is given.It is found that the impurity distribution after multiple diffusion processes can be characterized with an effective diffusion length.The relation between this effective diffusion length and the diffusion lengths of each diffusion process is given and shows itself to be very simple and instructive.The results of the expression agree well with numerical simulations by using SUPREMⅣ.An example of the application of the expression is also shown.
基金supported by the National Natural Science Foundation of China(52371163)Taishan Scholars Program of Shandong Province(tsqn202408154)+2 种基金China.F.M.appreciates the support from the Natural Science Foundation of Shandong Province(ZR2021QE110)Y.T.acknowledges the financial support by Taishan Scholars Program of Shandong Province(tsqn202103052)Yantai city matching fund for Taishan Scholars Program of Shandong Province,China.
文摘The influence of Nb,Co,Ti,and Al on the microstructural evolution and mechanical properties of GH4061 superalloy was simultaneously investigated using diffusion multiple techniques combined with double aging heat treatment.Co exhibited the highest penetration depth with monotonic concentration decrease,significantly inhibiting the formation of needle-likeδphase and reduced the precipitation size of theγ′phase.Nb diffusion formed distinct layers with clear interfaces,promoting substantialγ′′phase precipitation,while simultaneously enhancing hardness through solid solution strengthening.Ti and Al diffusion generated substantial diffusion layers containing Ti-Ni enriched needle-likeηphases and enhancedγ′phase growth,characterized by increased size and volume fraction compared to the base alloy.In contrast to the base alloy,this diffusion layer was devoid of phases enriched with Nb.Mechanical property analysis demonstrated that high concentrations of Nb,Al,and Ti enhanced alloy hardness through various strengthening mechanisms,whereas increased Co content diminished the size of theγ′phase at the interface,resulting in reduced hardness.This high-throughput experimental approach significantly reduced experimental workload while enabling detailed analysis of varying element concentrations on microstructure and properties.
