Ti-V-Fe-Mn body-centered cubic(BCC)solid solution alloys arouse extensive interests due to the superb hydrogen storage capacity.Understanding phase equilibrium that involves BCC phase is important when designing hydro...Ti-V-Fe-Mn body-centered cubic(BCC)solid solution alloys arouse extensive interests due to the superb hydrogen storage capacity.Understanding phase equilibrium that involves BCC phase is important when designing hydrogen storage materials.However,a reliable thermodynamic description of Ti-V-Fe-Mn system is lacking.To support thermodynamic modeling,ab initio calculations were conducted to determine formation enthalpies of theσand C14 Laves phases.The phase equilibria of Ti-V-Fe alloys at 1273 K and Ti-V-Mn alloys at 1273,1323 and 1373 K were investigated to elucidate the relationship between the BCC and C14 Laves phases.The thermodynamic parameters for the Ti-V-Fe system were revised.The thermodynamic description of the Ti-V-Mn system was established for the first time.Additionally,the V-Mn and V-Fe-Mn systems were thermodynamically reassessed for ensuring consistency in theσphase model.The computed results were comprehensively compared with experimental data,validating that model parameters were reliable.Furthermore,the thermodynamic database for the Ti-V-Fe-Mn system was adopted for predicting phase constitutions of as-cast hydrogen storage alloys,further demonstrating the practical applicability and reliability of the model parameters.展开更多
Microstructures and mechanical properties of Ti-V micro-alloyed TRIP（ transformation-induced plasticity） steel with different compositions were investigated by tensile test,scanning electron microscopy（ SEM）,trans...Microstructures and mechanical properties of Ti-V micro-alloyed TRIP（ transformation-induced plasticity） steel with different compositions were investigated by tensile test,scanning electron microscopy（ SEM）,transmission electron microscopy（ TEM）,X-ray diffraction（ XRD） and thermodynamic calculation（ TC）. The results indicated that the steel exhibited high ultimate tensile strength（ 1 079MPa）,sufficient ductility（ 28%） and the highest product of strength and ductility（ 30 212 MPa·%） heat treated after intercritical annealing at 800℃ for 3 min and bainitic annealing at 430 ℃ for 5 min. In addition,the change of volume fraction of retained austenite（ VF-RA） versus tensile strain was measured using in-situ analysis by X-ray stress apparatus and micro-electronic universal testing machine. It was concluded that a-value could be used to evaluate the stability of retained austenite（ S-RA） in the investigated Ti-V micro-alloyed TRIP steel. The smaller a-value indicated the higher stability of retained austenite（ S-RA） and the higher mechanical properties of Ti-V micro-alloyed TRIP steel.展开更多
By using a static and high-speed material testing machine, tensile deformation behaviors of two kinds of Si- Mn TRIP （transformation induced plasticity） steels and DP （dual phase） steel were studied in a large ran...By using a static and high-speed material testing machine, tensile deformation behaviors of two kinds of Si- Mn TRIP （transformation induced plasticity） steels and DP （dual phase） steel were studied in a large range of strain rates （0.001-2000 s 1）. Temperature variation during adiabatic heating and the amount of retained austenite at fracture were measured by an infrared thermometer and an Xray stress analyser, respectively. The microstructure of steels was observed by optical microscopy （OM） and scanning electron microscopy （SEM） before and after tensile test. It was found from the experimental results that the tensile strength of these steels increased, and the fracture elonga- tion firstly decreased and subsequently increased, as the strain rate increased in the range ＂of 0.1 - 2000 s -1. The temperature raised during adiabatic heating of TRIP steel was in the range of 100- 300℃, while that of the DP steel was in the range of 100-220℃ . The temperature rise of these steels increased with increasing the strain rate, as well as the amount of the transformed retained austenite in TRIP steels. It was confirmed that austenite to martensite transformation is not suppressed by adiabatic heating.展开更多
The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test,scanning electron microscopy（SEM）,transmission electron microscopy（TEM...The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）and thermodynamic calculation（TC）.It was shown that the ferrite-based lightweight steels with 5wt.%or 8wt.%Al were basically composed of ferrite,austenite andκ-carbide.As the annealing temperature increased,the content of the austenite in the steel gradually increased,while theκ-carbide gradually decomposed and finally disappeared.The mechanical properties of the steel with 5wt.%Al and 2wt.%Cr,composed of ferrite and Cr7C3carbide at different annealing temperatures,were significantly inferior to those of others.The steel containing 5wt.%Al,annealed at 820°C for 50sthen rapidly cooled to 400°C and held for 180s,can obtain the best product of strength and elongation（PSE）of 31242MPa·%.The austenite stability of the steel is better,and its PSE is higher.In addition,the steel with higher PSE has a more stable instantaneous strain hardening exponent（n value）,which is mainly caused by the effect of transformation induced plasticity（TRIP）.When theκ-carbide or Cr7C3carbide existed in the microstructure of the steel,there was an obvious yield plateau in the tensile curve,while its PSE decreased significantly.展开更多
The thermodynamic database of the Fe C Mn-Si system has been developed in the framework of the CALPHAD approach. The sub-ternary systems have been carefully evaluated and revised based on available experimental data. ...The thermodynamic database of the Fe C Mn-Si system has been developed in the framework of the CALPHAD approach. The sub-ternary systems have been carefully evaluated and revised based on available experimental data. A satisfactory description of the liquid phase in the Fe C-Si system has been obtained. The C Mn Si system was assessed treating the liquid phase as a substitutional solution. Phase equilibria in the C- Mn-Si system, especially those involving the liquid phase, can be well described. Based on the extrapolation of the experimental data in the quaternary system, the Fe Mn Si system has been modified to agree well with experimental data at high temperatures. The comparison between the calculated and measured phase transformation tempera tures confirms the reliability of the present quaternary database. Additionally, the solidification process of Fe-0. 16C-1. 5Mn-1. 5Si （wt. %） alloy was simulated by using the thermodynamic database developed.展开更多
The so-called low-density steels have generated a lot of interests with their high specific strength and ductility due to the addi-tion of the light element Al.ln order to accelerate the low-density steel design,a the...The so-called low-density steels have generated a lot of interests with their high specific strength and ductility due to the addi-tion of the light element Al.ln order to accelerate the low-density steel design,a thermodynamic database has been developedwithin the present author group.Two Al-containing systems,i.e.,Cr-Al-Cand Ni-Al-C,were modeled and optimirzed with CALPHAD approach based on the reliable binary descriptions.For Cr-Al-C,system,the Gibbs energy of Cr2AlC phasewas described by a temperature-dependent polynomial with the aid of the experimental data on the heat capacity,instead of estimating heat capacity from Ncumann-Kopp rule.The incongruent melting temperature of Cr2AlC is 1762 K with theinvariant reaction of liquid+Cr3C2+Al4C3→Cr2AlC.The phase equilibria between Cr2AlC and binary phases were wellreproduced by using the present model parameters.For Ni-Al-C system,the liquid,fec and bec phases have been optimizedto fit the carbon solubility in these three phases.A good agreement between the calculated and experimental data has beenobtained using the present description of Ni-Al-C system.The reliable descriptions of the two ternary systems developedin the present work can be implemented into the thermodynamic database for low-density steels.展开更多
Cyproheptadine （CPH）, a first-generation anti- histamine, enhances the delayed rectifier outward K＋ current （IK） in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this stu...Cyproheptadine （CPH）, a first-generation anti- histamine, enhances the delayed rectifier outward K＋ current （IK） in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH （10 μmol/L） significantly reduced the current density required to generate action potentials （APs） and increased the instan- taneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential （RMP）, decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mim- icked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium （TEA） to block IK channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive IK channels as well as other TEA-insensitive K＋ channels, probably ID and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.展开更多
Despite various studies on Co-Al-Fe ternary system, its phase equilibria are still in doubt. Phase equilibria, magnetic transition and bcc_A2/bcc_B2 order-disorder transformation at the Co-Fe-rich side of the Co-Al-Fe...Despite various studies on Co-Al-Fe ternary system, its phase equilibria are still in doubt. Phase equilibria, magnetic transition and bcc_A2/bcc_B2 order-disorder transformation at the Co-Fe-rich side of the Co-Al-Fe alloys were carefully investigated by means of electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calo-rimetry. The equilibrium phases and their compositions were determined by 18 alloy samples annealed at 900, 1000, 1100 and 1200℃ for 528, 336, 168 and 96h, respectively, followed by quenching. However, by adopting the above traditional method, bcc_A2 and fcc_A1 phases are difficult to be distinguished through XRD analysis at room temperature due to the martensitic transformation of fcc_A1 phase during quenching. For this reason, high-temperature insitu XRD technique was utilized to correctly establish the phase relationships among bcc_A2, bcc_B2 and fcc_A1 phases. The phase transformation between bcc_A2 and B2 phases was determined to be second order instead of first order at temperatures higher than 900℃. The equilibrium phases and compositions were further confirmed by fabricating 16 diffusion couples together with EPMA. Meanwhile, using three-dimensional differential scanning calorimetry method, bcc_A2/B2 and ferro-/paramagnetic transi-tions were determined with high accuracy.展开更多
Databases concerning basic physical properties of materials,such as molar volume,density,thermal expansion coefficient,elastic constants,thermal conductivity,etc.,are essential parts of the underlying knowledge for ma...Databases concerning basic physical properties of materials,such as molar volume,density,thermal expansion coefficient,elastic constants,thermal conductivity,etc.,are essential parts of the underlying knowledge for materials design.While thermodynamic databases provide chemical driving forces and phase equilibrium data,physical property databases provide essential physical parameters,such as volume,lattice constant,lattice misfit,elastic energy,interfacial energy,etc.,for phase transformation and microstructure simulations.Combined with thermodynamic databases,physical property databases established on the basis of the calculation of phase diagram(CALPHAD)method can be used to calculate physical properties together with phase equilibria,phase fractions,phase compositions,and thermodynamic properties for multi-component and multi-phase material systems and for the constituent phases.In this paper,we will discuss in detail various volume models based on the CALPHAD method which are capable of describing experimental data in a wide range from cryogenic temperatures to melting points,from the atmospheric pressure to high pressures for pure substances as well as multi-component and multiphase materials.展开更多
基金supported by the Natural Science Foundation of Shanghai(No.24ZR1425100)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.YESS20210357)+1 种基金the financial supports from the open foundation of Guangxi Key Laboratory of Information Materials,Guilin University of Electronic Technology(No.211009-K)State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy and the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200).
文摘Ti-V-Fe-Mn body-centered cubic(BCC)solid solution alloys arouse extensive interests due to the superb hydrogen storage capacity.Understanding phase equilibrium that involves BCC phase is important when designing hydrogen storage materials.However,a reliable thermodynamic description of Ti-V-Fe-Mn system is lacking.To support thermodynamic modeling,ab initio calculations were conducted to determine formation enthalpies of theσand C14 Laves phases.The phase equilibria of Ti-V-Fe alloys at 1273 K and Ti-V-Mn alloys at 1273,1323 and 1373 K were investigated to elucidate the relationship between the BCC and C14 Laves phases.The thermodynamic parameters for the Ti-V-Fe system were revised.The thermodynamic description of the Ti-V-Mn system was established for the first time.Additionally,the V-Mn and V-Fe-Mn systems were thermodynamically reassessed for ensuring consistency in theσphase model.The computed results were comprehensively compared with experimental data,validating that model parameters were reliable.Furthermore,the thermodynamic database for the Ti-V-Fe-Mn system was adopted for predicting phase constitutions of as-cast hydrogen storage alloys,further demonstrating the practical applicability and reliability of the model parameters.
基金supported by the Shanghai Municipal Science and Technology Commission(Grant No.15DZ2260300,15DZ2260301)Shanghai Municipal Natural Science Foundation(17ZR1410400)
文摘Microstructures and mechanical properties of Ti-V micro-alloyed TRIP（ transformation-induced plasticity） steel with different compositions were investigated by tensile test,scanning electron microscopy（ SEM）,transmission electron microscopy（ TEM）,X-ray diffraction（ XRD） and thermodynamic calculation（ TC）. The results indicated that the steel exhibited high ultimate tensile strength（ 1 079MPa）,sufficient ductility（ 28%） and the highest product of strength and ductility（ 30 212 MPa·%） heat treated after intercritical annealing at 800℃ for 3 min and bainitic annealing at 430 ℃ for 5 min. In addition,the change of volume fraction of retained austenite（ VF-RA） versus tensile strain was measured using in-situ analysis by X-ray stress apparatus and micro-electronic universal testing machine. It was concluded that a-value could be used to evaluate the stability of retained austenite（ S-RA） in the investigated Ti-V micro-alloyed TRIP steel. The smaller a-value indicated the higher stability of retained austenite（ S-RA） and the higher mechanical properties of Ti-V micro-alloyed TRIP steel.
基金Sponsored by National Natural Science Foundation of China(50934011,50971137)National Basic Research Program of China(2010CB630802)
文摘By using a static and high-speed material testing machine, tensile deformation behaviors of two kinds of Si- Mn TRIP （transformation induced plasticity） steels and DP （dual phase） steel were studied in a large range of strain rates （0.001-2000 s 1）. Temperature variation during adiabatic heating and the amount of retained austenite at fracture were measured by an infrared thermometer and an Xray stress analyser, respectively. The microstructure of steels was observed by optical microscopy （OM） and scanning electron microscopy （SEM） before and after tensile test. It was found from the experimental results that the tensile strength of these steels increased, and the fracture elonga- tion firstly decreased and subsequently increased, as the strain rate increased in the range ＂of 0.1 - 2000 s -1. The temperature raised during adiabatic heating of TRIP steel was in the range of 100- 300℃, while that of the DP steel was in the range of 100-220℃ . The temperature rise of these steels increased with increasing the strain rate, as well as the amount of the transformed retained austenite in TRIP steels. It was confirmed that austenite to martensite transformation is not suppressed by adiabatic heating.
基金supported by the Shanghai Municipal Natural Science Foundation(Grant No.17ZR1410400)the Shanghai Municipal Science and Technology Commission(Grant Nos.15DZ2260300,15DZ2260301)
文摘The microstructures and mechanical properties of ferrite-based lightweight steel with different compositions were investigated by tensile test,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）and thermodynamic calculation（TC）.It was shown that the ferrite-based lightweight steels with 5wt.%or 8wt.%Al were basically composed of ferrite,austenite andκ-carbide.As the annealing temperature increased,the content of the austenite in the steel gradually increased,while theκ-carbide gradually decomposed and finally disappeared.The mechanical properties of the steel with 5wt.%Al and 2wt.%Cr,composed of ferrite and Cr7C3carbide at different annealing temperatures,were significantly inferior to those of others.The steel containing 5wt.%Al,annealed at 820°C for 50sthen rapidly cooled to 400°C and held for 180s,can obtain the best product of strength and elongation（PSE）of 31242MPa·%.The austenite stability of the steel is better,and its PSE is higher.In addition,the steel with higher PSE has a more stable instantaneous strain hardening exponent（n value）,which is mainly caused by the effect of transformation induced plasticity（TRIP）.When theκ-carbide or Cr7C3carbide existed in the microstructure of the steel,there was an obvious yield plateau in the tensile curve,while its PSE decreased significantly.
基金the financial support from the Chinese National Key Project of Science and Technology (Grant No. 2012ZX06004-012)the support from the Chinese Scholarship Council (CSC)the support from the Shanghai Municipal Science and Technology Commission (Grant No. 15DZ2260300,15DZ2260301)
文摘The thermodynamic database of the Fe C Mn-Si system has been developed in the framework of the CALPHAD approach. The sub-ternary systems have been carefully evaluated and revised based on available experimental data. A satisfactory description of the liquid phase in the Fe C-Si system has been obtained. The C Mn Si system was assessed treating the liquid phase as a substitutional solution. Phase equilibria in the C- Mn-Si system, especially those involving the liquid phase, can be well described. Based on the extrapolation of the experimental data in the quaternary system, the Fe Mn Si system has been modified to agree well with experimental data at high temperatures. The comparison between the calculated and measured phase transformation tempera tures confirms the reliability of the present quaternary database. Additionally, the solidification process of Fe-0. 16C-1. 5Mn-1. 5Si （wt. %） alloy was simulated by using the thermodynamic database developed.
基金Thanks are given to the support from the NationalKey R&D Program of China(Grant No.2017YFB0304402)W.S.Zheng acknowledges the support from the Shanghai Sailing Program(Grant No.19YF1415700)the National Natural Science Foundation of China(Grant No.51901124).
文摘The so-called low-density steels have generated a lot of interests with their high specific strength and ductility due to the addi-tion of the light element Al.ln order to accelerate the low-density steel design,a thermodynamic database has been developedwithin the present author group.Two Al-containing systems,i.e.,Cr-Al-Cand Ni-Al-C,were modeled and optimirzed with CALPHAD approach based on the reliable binary descriptions.For Cr-Al-C,system,the Gibbs energy of Cr2AlC phasewas described by a temperature-dependent polynomial with the aid of the experimental data on the heat capacity,instead of estimating heat capacity from Ncumann-Kopp rule.The incongruent melting temperature of Cr2AlC is 1762 K with theinvariant reaction of liquid+Cr3C2+Al4C3→Cr2AlC.The phase equilibria between Cr2AlC and binary phases were wellreproduced by using the present model parameters.For Ni-Al-C system,the liquid,fec and bec phases have been optimizedto fit the carbon solubility in these three phases.A good agreement between the calculated and experimental data has beenobtained using the present description of Ni-Al-C system.The reliable descriptions of the two ternary systems developedin the present work can be implemented into the thermodynamic database for low-density steels.
基金supported by the National Natural Science Foundation of China(31370827)the Shanghai Leading Academic Discipline Project [B111]
文摘Cyproheptadine （CPH）, a first-generation anti- histamine, enhances the delayed rectifier outward K＋ current （IK） in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH （10 μmol/L） significantly reduced the current density required to generate action potentials （APs） and increased the instan- taneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential （RMP）, decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mim- icked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium （TEA） to block IK channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive IK channels as well as other TEA-insensitive K＋ channels, probably ID and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.
基金This work was financially supported by National Key R&D Program of China(Grant No.2017 YFB0701502).
文摘Despite various studies on Co-Al-Fe ternary system, its phase equilibria are still in doubt. Phase equilibria, magnetic transition and bcc_A2/bcc_B2 order-disorder transformation at the Co-Fe-rich side of the Co-Al-Fe alloys were carefully investigated by means of electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calo-rimetry. The equilibrium phases and their compositions were determined by 18 alloy samples annealed at 900, 1000, 1100 and 1200℃ for 528, 336, 168 and 96h, respectively, followed by quenching. However, by adopting the above traditional method, bcc_A2 and fcc_A1 phases are difficult to be distinguished through XRD analysis at room temperature due to the martensitic transformation of fcc_A1 phase during quenching. For this reason, high-temperature insitu XRD technique was utilized to correctly establish the phase relationships among bcc_A2, bcc_B2 and fcc_A1 phases. The phase transformation between bcc_A2 and B2 phases was determined to be second order instead of first order at temperatures higher than 900℃. The equilibrium phases and compositions were further confirmed by fabricating 16 diffusion couples together with EPMA. Meanwhile, using three-dimensional differential scanning calorimetry method, bcc_A2/B2 and ferro-/paramagnetic transi-tions were determined with high accuracy.
基金supported by the National Natural Science Foundation of China (51271106, 50934011)
文摘Databases concerning basic physical properties of materials,such as molar volume,density,thermal expansion coefficient,elastic constants,thermal conductivity,etc.,are essential parts of the underlying knowledge for materials design.While thermodynamic databases provide chemical driving forces and phase equilibrium data,physical property databases provide essential physical parameters,such as volume,lattice constant,lattice misfit,elastic energy,interfacial energy,etc.,for phase transformation and microstructure simulations.Combined with thermodynamic databases,physical property databases established on the basis of the calculation of phase diagram(CALPHAD)method can be used to calculate physical properties together with phase equilibria,phase fractions,phase compositions,and thermodynamic properties for multi-component and multi-phase material systems and for the constituent phases.In this paper,we will discuss in detail various volume models based on the CALPHAD method which are capable of describing experimental data in a wide range from cryogenic temperatures to melting points,from the atmospheric pressure to high pressures for pure substances as well as multi-component and multiphase materials.
