The behavior of void swelling and segregation in Fe-15Cr-xMn alloys and an alloy con- taining small amount of W and V was investigated by electron-irradiation.The compositional analysis in the irradiated regions inclu...The behavior of void swelling and segregation in Fe-15Cr-xMn alloys and an alloy con- taining small amount of W and V was investigated by electron-irradiation.The compositional analysis in the irradiated regions including grain boundaries was performed.The resultdts show that there are many common features of irradiuation tehavior in the Fe-Cr-Mn and Fe-Cr-Ni systems while there are some significant differences,In the Fe-Cr-Mn alloy sys- tems void swelling was rematrkably suppressed and at the same time the radiation-induced segregation was also retarded,furthermore,the segregation was strongly retarded in an Fe-15Cr-15Mn alloy containing small amount of W and V.The results also show that Ni re- placed by Mn does not in general confer immunity from either swelling or phase instabilities. The phase instability is due to the different diffusion behavior of Ni and Mn in reponse to the operation of the inverse-Kirkendall effecr.Fe segregates to the microstructural sinks in the Fe-Cr-Mn alloys.The segregation of Fe often leads to the formation of ferrite.This fact is beneficial to reducing the swelling rate and segregation on the grain boundaries.展开更多
Void swelling,which induces the degradation of the original properties of nuclear materials under high-energy particleirradiation,is an important problem.The incubation period,a transient stage before the steady void ...Void swelling,which induces the degradation of the original properties of nuclear materials under high-energy particleirradiation,is an important problem.The incubation period,a transient stage before the steady void growth,determines the duration of service of nuclear materials.Several experimental studies have been performed on void observations by transmission electron microscopy(TEM),which,however,has a resolution limit for the size of defect clusters.Positron annihilation lifetime spectroscopy(PALS)enables the detection of small vacancy clusters,single vacancies,dislocations and precipitates.The use of these two methods provides complementary information toward detecting defect information in the incubation period.Here,defect structures during the incubation period in austenitic stainless steels,by means of PALS and TEM are reviewed.The role of alloying elements into determining the period is explained.Furthermore,the existing problems and research directions in this field are presented.展开更多
Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume chan...Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume change in irradiated materials. Important material processes, including the generation of defects such as vacancies and self-interstitials, their diffusion and annihilation, and void nucleation and evolution, have been taken into account in this model. The thermodynamic and kinetic properties, such as chemical free energy, interfacial energy, vacancy mobility, and annihilation rate of vacancies and interstitials, are expressed as a function of temperature and/or defect concentrations in a general manner. The model allows for parametric studies of critical void nucleus size, void growth kinetics, and void volume fraction evolutions. Our simulations demonstrated that void swelling displays a quasi-bell shape distribution with temperature often observed in experiments.展开更多
文摘The behavior of void swelling and segregation in Fe-15Cr-xMn alloys and an alloy con- taining small amount of W and V was investigated by electron-irradiation.The compositional analysis in the irradiated regions including grain boundaries was performed.The resultdts show that there are many common features of irradiuation tehavior in the Fe-Cr-Mn and Fe-Cr-Ni systems while there are some significant differences,In the Fe-Cr-Mn alloy sys- tems void swelling was rematrkably suppressed and at the same time the radiation-induced segregation was also retarded,furthermore,the segregation was strongly retarded in an Fe-15Cr-15Mn alloy containing small amount of W and V.The results also show that Ni re- placed by Mn does not in general confer immunity from either swelling or phase instabilities. The phase instability is due to the different diffusion behavior of Ni and Mn in reponse to the operation of the inverse-Kirkendall effecr.Fe segregates to the microstructural sinks in the Fe-Cr-Mn alloys.The segregation of Fe often leads to the formation of ferrite.This fact is beneficial to reducing the swelling rate and segregation on the grain boundaries.
文摘Void swelling,which induces the degradation of the original properties of nuclear materials under high-energy particleirradiation,is an important problem.The incubation period,a transient stage before the steady void growth,determines the duration of service of nuclear materials.Several experimental studies have been performed on void observations by transmission electron microscopy(TEM),which,however,has a resolution limit for the size of defect clusters.Positron annihilation lifetime spectroscopy(PALS)enables the detection of small vacancy clusters,single vacancies,dislocations and precipitates.The use of these two methods provides complementary information toward detecting defect information in the incubation period.Here,defect structures during the incubation period in austenitic stainless steels,by means of PALS and TEM are reviewed.The role of alloying elements into determining the period is explained.Furthermore,the existing problems and research directions in this field are presented.
基金supported by the US Department of Energy’s Nuclear Energy Advance Modeling and Simulation (NEAMS) Program in Pacific Northwest National Laboratory, which is operated by Battelle Memorial Institute for the US Department of Energy (Grant No. DE-AC05- 76RL01830)Two of the authors (LI YuLan and GAO Fei) were partially supported by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, US Department of Energy
文摘Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume change in irradiated materials. Important material processes, including the generation of defects such as vacancies and self-interstitials, their diffusion and annihilation, and void nucleation and evolution, have been taken into account in this model. The thermodynamic and kinetic properties, such as chemical free energy, interfacial energy, vacancy mobility, and annihilation rate of vacancies and interstitials, are expressed as a function of temperature and/or defect concentrations in a general manner. The model allows for parametric studies of critical void nucleus size, void growth kinetics, and void volume fraction evolutions. Our simulations demonstrated that void swelling displays a quasi-bell shape distribution with temperature often observed in experiments.
