Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy,was investigated in 0.6 M NaCl solution and 0.6 M Na_(2)SO_(4)solution by scanning el...Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy,was investigated in 0.6 M NaCl solution and 0.6 M Na_(2)SO_(4)solution by scanning electron microscopy(SEM) observations, scanning Kelvin probe force microscopy(SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na_(2)SO_(4)solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na_(2)SO_(4)solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.展开更多
The second phase particle effect on texture evolution of polycrystalline material is studied through phase-field method. A unique field variable is introduced into the phase-field model to represent the second phase p...The second phase particle effect on texture evolution of polycrystalline material is studied through phase-field method. A unique field variable is introduced into the phase-field model to represent the second phase particles. Elastic interaction between particles and grains is also considered. Results indicate that in the presence of second phase particles the average particle diameter turns smaller than in the absence of these particles and retards texture formation by pinning effect. The second phase particles change the strain energy profile, which tremendously influences the pinning effect.展开更多
The second phase particle dispersed in microalloyed steel has different effects on grain growth depending on their size and volume fiaction of the second phase particles which will change during welding thermal cycles...The second phase particle dispersed in microalloyed steel has different effects on grain growth depending on their size and volume fiaction of the second phase particles which will change during welding thermal cycles. The particle coarsening and dissolution kinetics model was analyzed for continuous heating and cooling. In addition, based on experimental data, the coupled equation of grain growth was established by introducing limited size of grain growth with the consideration of the second phase particles pinning effects. Using Monte Carlo method based on experimental data model, the grain growth simulation for heat-affected zone of microalloyed steel welds was achieved. The calculating results were well in agreement with that of experiments.展开更多
On the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle (SPP) and grain boundary (GB) as viewed f...On the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle (SPP) and grain boundary (GB) as viewed from the applicability of grain boundary equation. Also, a new expression describing the interaction range has been derived, which solves the problem in theory that the interaction range between SPP and GB can only be qualitatively analyzed previously. It is shown that given the interaction position between SPP and GB, the interaction range can be quantitatively determined by use of this expression.展开更多
The effects of second phases on the fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated.The results show that the fracture mode can be generally described as ductile transgranular fracture in as-extruded con...The effects of second phases on the fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated.The results show that the fracture mode can be generally described as ductile transgranular fracture in as-extruded condition and intergranular fracture in peak-aged condition.In as-extruded condition,the ductile transgranular fracture occurs by the formation and transgranular propagation of the microcrack from the broken primary phases.However,as the collaboration effects of precipitates inside grains and on the grain boundaries have the tendency to reduce the cohesive strength of the grain boundary,and make the grain boundaries the favorable path for crack propagation,the intergranular fracture occurs in peak-aged condition.展开更多
Varying levels of dietary crude proteins and balanced amino acids were fed to layers for a period of eight weeks starting from the twenty-sixth week of age of birds and six weeks into egg production. Effects on perfor...Varying levels of dietary crude proteins and balanced amino acids were fed to layers for a period of eight weeks starting from the twenty-sixth week of age of birds and six weeks into egg production. Effects on performance and haematological characteristics were investigated at this second phase of production. Sixty Black Nera hens were randomly allotted into four (4) dietary treatments, containing the following levels of crude protein 14%, 15%, 16%, 17% and the metabolizable energy was iso-caloric for each treatment. The results showed that there were no significant differences (P > 0.05) observed for lymphocyte, Haemoglobin (Hb), Packed Cell Volume (PCV), Red Blood Cell (RBC) and White Blood Cell (WBC), these haematological parameters were within the range for healthy birds. Thus crude protein level of 14% can be used in diets of layers at the second phase of production provided that adequate amino acids are given, without adverse effect on egg laying, feed intake and measured blood parameters.展开更多
Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn.As-cast Zn and its alloys are brittle.Beside plastic deformation processing,no effective method has yet ...Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn.As-cast Zn and its alloys are brittle.Beside plastic deformation processing,no effective method has yet been found to eliminate the brittleness and even endow room temperature super-ductility.Second phase,induced by alloying,not only largely determines the ability of plastic deformation,but also influences strength,corrosion rate and cytotoxicity.Controlling second phase is important for designing biodegradable Zn alloys.In this review,knowledge related to second phases in biodegradable Zn alloys has been analyzed and summarized,including characteristics of binary phase diagrams,volume fraction of second phase in function of atomic percentage of an alloying element,and so on.Controversies about second phases in Zn-Li,Zn-Cu and Zn-Fe systems have been settled down,which benefits future studies.The effects of alloying elements and second phases on microstructure,strength,ductility,corrosion rate and cytotoxicity have been neatly summarized.Mg,Mn,Li,Cu and Ag are recommended as the major alloying elements,owing to their prominent beneficial effects on at least one of the above properties.In future,synergistic effects of these elements should be more thoroughly investigated.For other nutritional elements,such as Fe and Ca,refining second phase is a matter of vital concern.展开更多
Microstructure evolution and damping capacities of Mg–Ce binary alloys with three different Ce contents(0.5, 1, or 2 wt%) have been systematically investigated in this work. Numerous fine parallel second phases in...Microstructure evolution and damping capacities of Mg–Ce binary alloys with three different Ce contents(0.5, 1, or 2 wt%) have been systematically investigated in this work. Numerous fine parallel second phases in Mg–2Ce alloy are obtained, as well as a large number of dislocations around them, but few dislocations appear around the reticular second phase in the Mg–1Ce alloy. Among the three alloys, two internal friction peaks(P;and P;) are detected at about 78 and 167?C in both the Mg–0.5Ce and Mg–1Ce alloys.In addition, the alloy with special parallel second phase structure exhibits excellent damping capacity in both strain amplitude and temperature-dependent regions. These results may be ascribed to the stress concentration and the formation of abundant parallel and uniform dislocation configurations in the ?-Mg matrix without the influence of crystal orientation. The obtained results may provide a novel idea to prepare high-damping magnesium alloys by tailoring their microstructure.展开更多
Two types of stress relaxation tests were carried out to investigate the incubation time for incipient precipi-tation of Ti(C,N) in deformed austenite and (Ti,Mo)C in ferrite of ferritic Ti-Mo microalloyed steel T...Two types of stress relaxation tests were carried out to investigate the incubation time for incipient precipi-tation of Ti(C,N) in deformed austenite and (Ti,Mo)C in ferrite of ferritic Ti-Mo microalloyed steel The size dis-tribution, amount and chemical composition of precipitates were obtained by using physicochemical phase analysis, and calculated according to thermodynamics and kinetics. The experimental results demonstrated that the incubation time was reduced with increasing Ti content, and prolonged with the addition of Mo. After 30 % deformation at 850 ℃, the nucleation of strain-induced Ti(C,N) was a relatively slow process. On the other hand, the temperature where the nucleation rate of (Ti, Mo)C in ferrite was the highest descended first and then ascended with increasing Ti content, and so did the temperature where the incubation time was the shortest. The key point is that the tempera-ture of steel containing about 0.09 % Ti is the lowest. The mass fraction of MC-type particles with size smaller than 10 nm in steel containing 0.09% Ti and 0.2% Mo reached 73.7%. The size distributions of precipitates in steel containing 0.09% Ti were relatively concentrated compared with that in steel containing 0.07% Ti.展开更多
The selective abnormal growth of Goss grains in magnetic sheets of Fe-3%Si (grade Hi-B) induced by second-phase particles (AlN and MnS) was studied using a modified Monte Carlo Ports model. The starting microstruc...The selective abnormal growth of Goss grains in magnetic sheets of Fe-3%Si (grade Hi-B) induced by second-phase particles (AlN and MnS) was studied using a modified Monte Carlo Ports model. The starting microstructures for the simulations were generated from electron backscatter diffraction (EBSD) orientation imaging maps of recrystallized samples. In the simulation, second-phase particles were assumed to be randomly distributed in the initial microstructures and the Zener drag effect of particles on Goss grain boundaries was assumed to be selectively invalid because of the unique properties of Goss grain boundaries. The simulation results suggest that normal growth of the matrix grains stagnates because of the pinning effect of particles on their boundaries. During the onset of abnormal grain growth, some Goss grains with concave boundaries in the initial microstructure grow fast abnormally and other Goss grains with convex boundaries shrink and eventually disappear.展开更多
In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were investigated.Isothermal annealing...In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were investigated.Isothermal annealing was conducted on a Gleeble-1500 thermo-mechanical simulator.The mean grain size Dg of each annealed specimen was measured by the quantitative metallography technique.The grain growth kinetics of the Mg-6Zn alloy annealed at 473-623 K was obtained as Dg^4- Dg0^4=2.25 ×10^11 exp(-95450)by the least square linear regression method.The deviation of grain growth exponent n = 4 from the theoretical value of 2 may be attributed to the presence of solute zinc and second phases which will retard the boundary migration.Microscopic observations show that the non-uniform distribution of grain size for samples pre-extruded or annealed at low temperatures is closely related to the non-uniform distribution of fine and dispersed second phases but not to the non-uniform distribution of solute zinc.This indicates that second phase pinning effect plays an important role in microstructure refinement.展开更多
The second phase in multi-phase alloys has connection with many important phenomena such as aging strengthening,dispersion strengthening,secondary hardening,crystal refinement.In this paper,the interface conjunction f...The second phase in multi-phase alloys has connection with many important phenomena such as aging strengthening,dispersion strengthening,secondary hardening,crystal refinement.In this paper,the interface conjunction factors of the interface between MC(M=V,Nb,Ti) and austenite and martensite are calculate out.The relationship between these factors and the characteristics are analyzed.The reason for the second phases being fine and dispersing and their strengthening and toughening effect on the alloy is explained using the relationship.Based on the relationship,the valence electron structure of the interface between the second phase particles and the matrix can be optimized by changing the alloying elements,which make it possible to design the composition of alloys from the valence electron structure of the second phase particles.展开更多
Recent observations by electron microscopy have shown that a dislocation-free zone (DFZ) exists between the crack tip and the pile-up of dislocations in the plastic zone. Shang, S. J., Ohr, S. M. and Majumdar, B. S., ...Recent observations by electron microscopy have shown that a dislocation-free zone (DFZ) exists between the crack tip and the pile-up of dislocations in the plastic zone. Shang, S. J., Ohr, S. M. and Majumdar, B. S., Burns, S. J. have discussed the problem of the plastic zone at a crack tip in isotropic elastic medium. We know that the hard second phase, which neither causes very large stress concentration nor leads to micrographic split, can improve the bearing capacity of the materials. Therefore, it is necessary to discuss the problem of the plastic zone at a crack tip while the hard second phase exists.展开更多
A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the b...A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the bubble and liquid velocities, bubble volume fraction, bubble and liquid Reynolds stresses and bubble-liquidvelocity correlation. For predicted two-phase velocities and bubble volume fraction there is only slight differencebetween these two models, and the simulation results using both two models are in good agreement with the particleimage velocimetry (PIV) measurements. Although the predicted two-phase Reynolds stresses using the FSM are insomewhat better agreement with the PIV measurements than those predicted using the ASM, the Reynolds stressespredicted using both two models are in general agreement with the experiments. Therefore, it is suggested to usethe ASM two-phase turbulence model in engineering application for saving the computation time.展开更多
A two-scale second-order moment two-phase turbulence model accounting for inter-particle collision is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluc...A two-scale second-order moment two-phase turbulence model accounting for inter-particle collision is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The proposed model is used to simulate gas-particle downer reactor flows. The computational results of both particle volume fraction and mean velocity are in agreement with the experimental results. After analyzing effects of empirical coefficient on prediction results, we can come to a conclusion that, inside the limit range of empirical coefficient, the predictions do not reveal a large sensitivity to the empirical coefficient in the downer reactor, but a relatively great change of the constants has important effect on the prediction.展开更多
Background: Capecitabine and irinotecan combination therapy(XELIRI) has been examined at various dose levels to treat metastatic colorectal cancer(m CRC). Recently, in the Association of Medical Oncology of the German...Background: Capecitabine and irinotecan combination therapy(XELIRI) has been examined at various dose levels to treat metastatic colorectal cancer(m CRC). Recently, in the Association of Medical Oncology of the German Cancer Society(AIO) 0604 trial, tri?weekly XELIRI plus bevacizumab, with reduced doses of irinotecan(200 mg/m^2 on day 1) and capecitabine(1600 mg/m^2 on days 1–14), repeated every 3 weeks, has shown favorable tolerability and eicacy which were comparable to those of capecitabine and oxaliplatin(XELOX) plus bevacizumab. The doses of capecit?abine and irinotecan in the AIO trial are considered optimal. In a phase I/II study, XELIRI plus bevacizumab(BIX) as second?line chemotherapy was well tolerated and had promising eicacy in Japanese patients.Methods: The Asian XELIRI Projec T(AXEPT) is an East Asian collaborative, open?labelled, randomized, phase Ⅲ clinical trial which was designed to demonstrate the non?inferiority of XELIRI with or without bevacizumab versus standard FOLFIRI(5?fluorouracil, leucovorin, and irinotecan combination) with or without bevacizumab as second?line chemo?therapy for patients with m CRC. Patients with 20 years of age or older, histologically conirmed m CRC, Eastern Coop?erative Oncology Group performance status 0–2, adequate organ function, and disease progression or intolerance of the irst?line regimen will be eligible. Patients will be randomized(1:1) to receive standard FOLFIRI with or with?out bevacizumab(5 mg/kg on day 1), repeated every 2 weeks(FOLIRI arm) or XELIRI with or without bevacizumab(7.5 mg/kg on day 1), repeated every 3 weeks(XELIRI arm). A total of 464 events were estimated as necessary to show non?inferiority with a power of 80% at a one?sided α of 0.025, requiring a target sample size of 600 patients. The 95% conidence interval(CI) upper limit of the hazard ratio was pre?speciied as less than 1.3.Conclusion: The Asian XELIRI Projec T is a multinational phase III trial being conducted to provide evidence for XELIRI with or without bevacizumab as a second?line treatment option of mCRC.展开更多
The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collisi...The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. In this model, phases interaction and the extra term of Bingham fluid yield stress are taken into account. An algorithm for USM-θ model in dense two-phase flow was proposed, in which the influence of particle volume fraction is accounted for. This model was used to simulate turbulent flow of Bingham fluid single-phase and dense liquid-particle two-phase in pipe. It is shown USM-θ model has better prediction result than the five-equation model, in which the particle-particle collision is modeled by the particle kinetic theory, while the turbulence of both phase is simulated by the two-equation turbulence model. The USM-θ model was then used to simulate the dense two-phase turbulent up flow of Bingham fluid with particles. With the increasing of the yield stress, the velocities of Bingham and particle decrease near the pipe centre. Comparing the two-phase flow of Bingham-particle with that of liquid-particle, it is found the source term of yield stress has significant effect on flow.展开更多
基金funded by the National Key Research and Development Program of China (Grant No. 2016YFB0301001 and 2016YFB0301101)Major Projects for Collaborative Innovation of Zhengzhou (Grant No.18XTZX12010)Certificate of Postdoctoral Research Grant in Henan Province (Grant No. 201903011)。
文摘Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy,was investigated in 0.6 M NaCl solution and 0.6 M Na_(2)SO_(4)solution by scanning electron microscopy(SEM) observations, scanning Kelvin probe force microscopy(SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na_(2)SO_(4)solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na_(2)SO_(4)solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.
基金supported by the National Natural Science Foundation of China(Grant Nos.51174168,and 51274167)"111"Project,China(Grant No.B08040)
文摘The second phase particle effect on texture evolution of polycrystalline material is studied through phase-field method. A unique field variable is introduced into the phase-field model to represent the second phase particles. Elastic interaction between particles and grains is also considered. Results indicate that in the presence of second phase particles the average particle diameter turns smaller than in the absence of these particles and retards texture formation by pinning effect. The second phase particles change the strain energy profile, which tremendously influences the pinning effect.
文摘The second phase particle dispersed in microalloyed steel has different effects on grain growth depending on their size and volume fiaction of the second phase particles which will change during welding thermal cycles. The particle coarsening and dissolution kinetics model was analyzed for continuous heating and cooling. In addition, based on experimental data, the coupled equation of grain growth was established by introducing limited size of grain growth with the consideration of the second phase particles pinning effects. Using Monte Carlo method based on experimental data model, the grain growth simulation for heat-affected zone of microalloyed steel welds was achieved. The calculating results were well in agreement with that of experiments.
基金the financial support from the Supporting Plan for New Century Excellent Talents,MOE,China under grant No.NCET-04-0257the National Natural Science Foundation of China(No.50471070)the Natural Science Foundation of Shanxi Province(No.20051050).
文摘On the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle (SPP) and grain boundary (GB) as viewed from the applicability of grain boundary equation. Also, a new expression describing the interaction range has been derived, which solves the problem in theory that the interaction range between SPP and GB can only be qualitatively analyzed previously. It is shown that given the interaction position between SPP and GB, the interaction range can be quantitatively determined by use of this expression.
基金Project(IRT0713)supported by the Program for Changjiang Scholars and Innovative Research Team in Chinese UniversityProjects(2007CB613701,2007CB613702)supported by National Basic Research Program of China
文摘The effects of second phases on the fracture behavior of Mg-10Gd-3Y-0.6Zr alloy were investigated.The results show that the fracture mode can be generally described as ductile transgranular fracture in as-extruded condition and intergranular fracture in peak-aged condition.In as-extruded condition,the ductile transgranular fracture occurs by the formation and transgranular propagation of the microcrack from the broken primary phases.However,as the collaboration effects of precipitates inside grains and on the grain boundaries have the tendency to reduce the cohesive strength of the grain boundary,and make the grain boundaries the favorable path for crack propagation,the intergranular fracture occurs in peak-aged condition.
文摘Varying levels of dietary crude proteins and balanced amino acids were fed to layers for a period of eight weeks starting from the twenty-sixth week of age of birds and six weeks into egg production. Effects on performance and haematological characteristics were investigated at this second phase of production. Sixty Black Nera hens were randomly allotted into four (4) dietary treatments, containing the following levels of crude protein 14%, 15%, 16%, 17% and the metabolizable energy was iso-caloric for each treatment. The results showed that there were no significant differences (P > 0.05) observed for lymphocyte, Haemoglobin (Hb), Packed Cell Volume (PCV), Red Blood Cell (RBC) and White Blood Cell (WBC), these haematological parameters were within the range for healthy birds. Thus crude protein level of 14% can be used in diets of layers at the second phase of production provided that adequate amino acids are given, without adverse effect on egg laying, feed intake and measured blood parameters.
基金financially supported by National Key R&D Program of China(2016YFC1102500).
文摘Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn.As-cast Zn and its alloys are brittle.Beside plastic deformation processing,no effective method has yet been found to eliminate the brittleness and even endow room temperature super-ductility.Second phase,induced by alloying,not only largely determines the ability of plastic deformation,but also influences strength,corrosion rate and cytotoxicity.Controlling second phase is important for designing biodegradable Zn alloys.In this review,knowledge related to second phases in biodegradable Zn alloys has been analyzed and summarized,including characteristics of binary phase diagrams,volume fraction of second phase in function of atomic percentage of an alloying element,and so on.Controversies about second phases in Zn-Li,Zn-Cu and Zn-Fe systems have been settled down,which benefits future studies.The effects of alloying elements and second phases on microstructure,strength,ductility,corrosion rate and cytotoxicity have been neatly summarized.Mg,Mn,Li,Cu and Ag are recommended as the major alloying elements,owing to their prominent beneficial effects on at least one of the above properties.In future,synergistic effects of these elements should be more thoroughly investigated.For other nutritional elements,such as Fe and Ca,refining second phase is a matter of vital concern.
基金financially supported by the National Natural Science Foundation of China (No. 51271206, No. 51571044)the National Basic Research Program of China (No. 2013CB632201)+1 种基金the Basic Research Project of Chongqing (cstc2015jcyj BX0081)National Key Research and Development Program (No. 2016YFB0301102)
文摘Microstructure evolution and damping capacities of Mg–Ce binary alloys with three different Ce contents(0.5, 1, or 2 wt%) have been systematically investigated in this work. Numerous fine parallel second phases in Mg–2Ce alloy are obtained, as well as a large number of dislocations around them, but few dislocations appear around the reticular second phase in the Mg–1Ce alloy. Among the three alloys, two internal friction peaks(P;and P;) are detected at about 78 and 167?C in both the Mg–0.5Ce and Mg–1Ce alloys.In addition, the alloy with special parallel second phase structure exhibits excellent damping capacity in both strain amplitude and temperature-dependent regions. These results may be ascribed to the stress concentration and the formation of abundant parallel and uniform dislocation configurations in the ?-Mg matrix without the influence of crystal orientation. The obtained results may provide a novel idea to prepare high-damping magnesium alloys by tailoring their microstructure.
基金Item Sponsored by National Key Technology Research and Development Program in 11th Five-Year Plan of China (2006BE03A0)
文摘Two types of stress relaxation tests were carried out to investigate the incubation time for incipient precipi-tation of Ti(C,N) in deformed austenite and (Ti,Mo)C in ferrite of ferritic Ti-Mo microalloyed steel The size dis-tribution, amount and chemical composition of precipitates were obtained by using physicochemical phase analysis, and calculated according to thermodynamics and kinetics. The experimental results demonstrated that the incubation time was reduced with increasing Ti content, and prolonged with the addition of Mo. After 30 % deformation at 850 ℃, the nucleation of strain-induced Ti(C,N) was a relatively slow process. On the other hand, the temperature where the nucleation rate of (Ti, Mo)C in ferrite was the highest descended first and then ascended with increasing Ti content, and so did the temperature where the incubation time was the shortest. The key point is that the tempera-ture of steel containing about 0.09 % Ti is the lowest. The mass fraction of MC-type particles with size smaller than 10 nm in steel containing 0.09% Ti and 0.2% Mo reached 73.7%. The size distributions of precipitates in steel containing 0.09% Ti were relatively concentrated compared with that in steel containing 0.07% Ti.
基金financially supported by the National Key Research and Development Program of China(No 2016YFB0700505)the China’s State Grid Corporation of Science and Technology Projects(No.SGRI-WD71-13-002)+1 种基金the National Natural Science Foundation of China(Nos.51571020 and 51371030)the Nationa High Technology Research and Development Program of China(No.2015AA034201)
文摘The selective abnormal growth of Goss grains in magnetic sheets of Fe-3%Si (grade Hi-B) induced by second-phase particles (AlN and MnS) was studied using a modified Monte Carlo Ports model. The starting microstructures for the simulations were generated from electron backscatter diffraction (EBSD) orientation imaging maps of recrystallized samples. In the simulation, second-phase particles were assumed to be randomly distributed in the initial microstructures and the Zener drag effect of particles on Goss grain boundaries was assumed to be selectively invalid because of the unique properties of Goss grain boundaries. The simulation results suggest that normal growth of the matrix grains stagnates because of the pinning effect of particles on their boundaries. During the onset of abnormal grain growth, some Goss grains with concave boundaries in the initial microstructure grow fast abnormally and other Goss grains with convex boundaries shrink and eventually disappear.
基金the financial support from the National Natural Science Foundation of China(Grant No.51105328)the Natural Science Foundation of Jiangsu Province of China(No.BK20130447)the Colleges and Universities in Jiangsu Province Natural Science Foundation of China(Grant No.13KJB430026)
文摘In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were investigated.Isothermal annealing was conducted on a Gleeble-1500 thermo-mechanical simulator.The mean grain size Dg of each annealed specimen was measured by the quantitative metallography technique.The grain growth kinetics of the Mg-6Zn alloy annealed at 473-623 K was obtained as Dg^4- Dg0^4=2.25 ×10^11 exp(-95450)by the least square linear regression method.The deviation of grain growth exponent n = 4 from the theoretical value of 2 may be attributed to the presence of solute zinc and second phases which will retard the boundary migration.Microscopic observations show that the non-uniform distribution of grain size for samples pre-extruded or annealed at low temperatures is closely related to the non-uniform distribution of fine and dispersed second phases but not to the non-uniform distribution of solute zinc.This indicates that second phase pinning effect plays an important role in microstructure refinement.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59631060) .
文摘The second phase in multi-phase alloys has connection with many important phenomena such as aging strengthening,dispersion strengthening,secondary hardening,crystal refinement.In this paper,the interface conjunction factors of the interface between MC(M=V,Nb,Ti) and austenite and martensite are calculate out.The relationship between these factors and the characteristics are analyzed.The reason for the second phases being fine and dispersing and their strengthening and toughening effect on the alloy is explained using the relationship.Based on the relationship,the valence electron structure of the interface between the second phase particles and the matrix can be optimized by changing the alloying elements,which make it possible to design the composition of alloys from the valence electron structure of the second phase particles.
文摘Recent observations by electron microscopy have shown that a dislocation-free zone (DFZ) exists between the crack tip and the pile-up of dislocations in the plastic zone. Shang, S. J., Ohr, S. M. and Majumdar, B. S., Burns, S. J. have discussed the problem of the plastic zone at a crack tip in isotropic elastic medium. We know that the hard second phase, which neither causes very large stress concentration nor leads to micrographic split, can improve the bearing capacity of the materials. Therefore, it is necessary to discuss the problem of the plastic zone at a crack tip while the hard second phase exists.
基金Supported by the Special Funds for Major State Basic Research Projects, PRC(G1999-0222-08) and the National Natural Science Foundation of China(No. 19872039).
文摘A full second-order moment (FSM) model and an algebraic stress (ASM) two-phase turbulence modelare proposed and applied to predict turbulent bubble-liquid flows in a 2D rectangular bubble column. Predictiongives the bubble and liquid velocities, bubble volume fraction, bubble and liquid Reynolds stresses and bubble-liquidvelocity correlation. For predicted two-phase velocities and bubble volume fraction there is only slight differencebetween these two models, and the simulation results using both two models are in good agreement with the particleimage velocimetry (PIV) measurements. Although the predicted two-phase Reynolds stresses using the FSM are insomewhat better agreement with the PIV measurements than those predicted using the ASM, the Reynolds stressespredicted using both two models are in general agreement with the experiments. Therefore, it is suggested to usethe ASM two-phase turbulence model in engineering application for saving the computation time.
基金Project supported by China Post-Doctoral Science Foundation(No.2004036239)
文摘A two-scale second-order moment two-phase turbulence model accounting for inter-particle collision is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The proposed model is used to simulate gas-particle downer reactor flows. The computational results of both particle volume fraction and mean velocity are in agreement with the experimental results. After analyzing effects of empirical coefficient on prediction results, we can come to a conclusion that, inside the limit range of empirical coefficient, the predictions do not reveal a large sensitivity to the empirical coefficient in the downer reactor, but a relatively great change of the constants has important effect on the prediction.
基金funding from Chugai Pharmaceutical Co.Ltd.Roche Korea Co.Ltd.Roche Shanghai.Co.Ltd
文摘Background: Capecitabine and irinotecan combination therapy(XELIRI) has been examined at various dose levels to treat metastatic colorectal cancer(m CRC). Recently, in the Association of Medical Oncology of the German Cancer Society(AIO) 0604 trial, tri?weekly XELIRI plus bevacizumab, with reduced doses of irinotecan(200 mg/m^2 on day 1) and capecitabine(1600 mg/m^2 on days 1–14), repeated every 3 weeks, has shown favorable tolerability and eicacy which were comparable to those of capecitabine and oxaliplatin(XELOX) plus bevacizumab. The doses of capecit?abine and irinotecan in the AIO trial are considered optimal. In a phase I/II study, XELIRI plus bevacizumab(BIX) as second?line chemotherapy was well tolerated and had promising eicacy in Japanese patients.Methods: The Asian XELIRI Projec T(AXEPT) is an East Asian collaborative, open?labelled, randomized, phase Ⅲ clinical trial which was designed to demonstrate the non?inferiority of XELIRI with or without bevacizumab versus standard FOLFIRI(5?fluorouracil, leucovorin, and irinotecan combination) with or without bevacizumab as second?line chemo?therapy for patients with m CRC. Patients with 20 years of age or older, histologically conirmed m CRC, Eastern Coop?erative Oncology Group performance status 0–2, adequate organ function, and disease progression or intolerance of the irst?line regimen will be eligible. Patients will be randomized(1:1) to receive standard FOLFIRI with or with?out bevacizumab(5 mg/kg on day 1), repeated every 2 weeks(FOLIRI arm) or XELIRI with or without bevacizumab(7.5 mg/kg on day 1), repeated every 3 weeks(XELIRI arm). A total of 464 events were estimated as necessary to show non?inferiority with a power of 80% at a one?sided α of 0.025, requiring a target sample size of 600 patients. The 95% conidence interval(CI) upper limit of the hazard ratio was pre?speciied as less than 1.3.Conclusion: The Asian XELIRI Projec T is a multinational phase III trial being conducted to provide evidence for XELIRI with or without bevacizumab as a second?line treatment option of mCRC.
基金Project supported by the National Key Basic Research and Development Program of China(No.G1999-0222-08)
文摘The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. In this model, phases interaction and the extra term of Bingham fluid yield stress are taken into account. An algorithm for USM-θ model in dense two-phase flow was proposed, in which the influence of particle volume fraction is accounted for. This model was used to simulate turbulent flow of Bingham fluid single-phase and dense liquid-particle two-phase in pipe. It is shown USM-θ model has better prediction result than the five-equation model, in which the particle-particle collision is modeled by the particle kinetic theory, while the turbulence of both phase is simulated by the two-equation turbulence model. The USM-θ model was then used to simulate the dense two-phase turbulent up flow of Bingham fluid with particles. With the increasing of the yield stress, the velocities of Bingham and particle decrease near the pipe centre. Comparing the two-phase flow of Bingham-particle with that of liquid-particle, it is found the source term of yield stress has significant effect on flow.