ISSN:1042-0150    

DOI:10.1080/10420159908229101

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A number of recent problems in structural materials for nuclear energy systems require quantitative and reliable predictions of materials behaviour in as yet unrealized operating conditions. An example is found in pressure vessel steels of a light water reactor, where prediction of embrittlement of the steel for extended period of service must be done with confidence, because the integrity of the pressure vessel is of vital importance for the safety of the light water reactor. Light water reactor fuel, cladding and wrapper of a fast breeder reactor and first wall and blanket structural materials of a fusion reactor are such examples that are briefly discussed. In such problems, we have either scarce data or limited and rather irrelevant data of the materials performance for the service conditions of the materials in question. The method used to predict the irradiation behaviour of materials from incomplete existing data is called irradiation correlation. The correlation methodology is discussed. To describe the materials behaviour, the component processes should be modelled in terms of elemental defect processes. These models are then integrated to describe the materials behaviour.

ISSN:1042-0150    

DOI:10.1080/10420159908229102

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We have been requested to prepare a rather unusual article for this special publication. The article should be not only autobiographical in nature but should also have historical perspectives and critique and should contain some element of visionary forecast. Undoubtedly, the idea is unique and challenging though may prove to be less than easy to realise!

ISSN:1042-0150    

DOI:10.1080/10420159908229103

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Several fundamental aspects of defect cluster accumulation in irradiated ceramics and face centered cubic metals are reviewed, with particular emphasis on radiation hardening and the microstructural evolution in Cu observed by transmission electron microscopy (TEM). At temperatures where interstitials are mobile (> 50 K in Cu), the defect cluster density in pure Cu is initially proportional to the dose and exhibits a square root dose dependence above ∼ 10−4displacements per atom. This fluence dependence (determined from electrical resistivity and TEM studies) helps to resolve a long-standing controversy on the fluence dependence of radiation hardening. The fraction of freely migrating interstitials in copper irradiated with 14 MeV neutrons at room temperature is ∼ 11%. The activation energy for annealing stage V (stacking fault tetrahedra evaporation) in neutron-irradiated copper has been measured to be 0.84eV. Some features of the point defect accumulation behavior in ceramics are found to be very similar to the trends observed in pure Cu, despite the obvious differences in the physical properties of these two types of materials. Finally, microstructural evidence for some processes unique to nonmetals are summarized, particularly ionization induced diffusion.

ISSN:1042-0150    

DOI:10.1080/10420159908229104

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A review is presented of a very general aspect of the response of all metals subjected to displacive irradiation. This aspect is referred to as «persistence» and describes the tendency of both radiation-induced microstructural evolution and the associated changes in material properties or dimensional stability to evolve to saturation states that resist further change upon continued irradiation. It is shown that new persistent states can develop on a longer time frame associated with the late-term loss of existing microstructural components or the gain of new components, especially when transmutation and/or segregation occurs. The persistent states are often dependent on the irradiation conditions, and if these are changed, the material usually adjusts to form the persistent state characteristic of the new conditions, with the memory of the former state often lost, and sometimes leaving no visible record of the former state in the new microstructure. Depending on the microstructural components involved, the transition toward the new persistent state can occur quickly or very slowly.

ISSN:1042-0150    

DOI:10.1080/10420159908229105

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159908229106

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The general peculiarities of grain boundary fracture of irradiated materials are discussed. Such physical phenomena as high temperature helium embrittlement of structural fusion materials and irradiation-assisted stress corrosion cracking of austenitic alloys in nuclear reactor core components under neutron irradiation are characterized by the ductility loss and intergranular fracture. In fission and fusion structural materials due to (n, α) and (n, p) reactions, high concentrations of helium and hydrogen can be generated. The effects of accumulation of gaseous (helium, hydrogen) atoms, segregation of solute impurity atoms at grain boundaries (GBs) and grain boundary sliding process of fracture of irradiated materials are discussed. At high temperatures, in irradiated materials containing helium atoms the system of helium bubbles is formed. In stressed materials, the kinetics of helium bubble growth on GBs is considered. The effect of grain boundary bubbles and bubbles on triple grain junctions (TGJs) on the fracture of irradiated alloys is analyzed elsewhere. The fracture process in these conditions is modeled in terms of interaction of bubble arrays on TGJs with a pile up of dislocations during creep and grain boundary sliding. Fracture criteria for a material are formulated in their dependence upon bubble density and size, gas content in bubbles on TGJs and time scale of crack growth.

ISSN:1042-0150    

DOI:10.1080/10420159908229107

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Radiation damage formed in metal specimens exposed to long pulse tokamak plasmas of TRIAM-1M was examined by transmission electron microscopy. By comparing these results with those of low energy hydrogen ion irradiation it was concluded that the charge exchange energetic neutrals of hydrogen emitted from the core plasma caused remarkable displacement damage. The flux of the neutrals in the energy range of 0.5–3 keV which were responsible for displacement damage, was estimated to be about 1.5–3 × 1018H/m2/s. These energetic neutrals cause not only material degradation at the sub-surface region but also change bulk properties of plasma facing components in a plasma confinement device. Effect of helium plasma was also discussed with emphasis on very strong effects on damage accumulation. Damage by He is a serious issue of plasma facing materials.

ISSN:1042-0150    

DOI:10.1080/10420159908229108

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Multilayer structured alloys which have a layer thickness less than 10 nm have been produced by the application of repeated pressing and rolling to the initially macroscopically thick layered sample. The TEM observation of a Ag/Fe sample revealed a regular alternate lamination of Ag and Fe with the layer thickness in the range of 10 nm. The measured electrical resistivity showed a large dependence on the applied magnetic field which is characteristic to the composite structure of magnetic and non-magnetic metals in the thickness range of nanometers.

ISSN:1042-0150    

DOI:10.1080/10420159908229109

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159908229080

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor