摘要:

Damage production, radiation annealing and stage I recovery in some FCC metals irradiated with ∼ 1 MeV and ∼ 100 MeV ions near 10 K are studied using electrical resistivity measurements. For ∼ 1 MeV light and heavy ion irradiations, the fraction of stage I recovery and the damage efficiency decrease with the PKA median energy. For ∼ 100 MeV heavy ion irradiations, an anomalous reduction of stage I recovery and a large cross-section for subthreshold recombination are found in Ni, and an enhancement of the damage efficiency is found in Cu; they are interpreted as due to the electron excitation by irradiating ions and the subsequent energy transfer from excited electrons to lattice atoms. Simultaneous differential equations describing the production and radiation annealing of two or more types of defects are solved, where the respective defect concentration is expressed as a function of fluence.

ISSN:1042-0150    

DOI:10.1080/10420159008213060

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159008213061

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159008213062

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Cascade size may affect phase stability under irradiation because of two distinct contributions: the replacement to displacement cross-section ratio depends on the deposited energy density; ballistic jumps which tend to disorder ordered compounds occur by bursts, while thermal jumps which restore long range order occur one by one.

ISSN:1042-0150    

DOI:10.1080/10420159008213063

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The simultaneous production of helium atoms and collision cascades during irradiation may enhance the nucleation of cavities. The influence of parameters such as helium generation rate and recoil energy on the possibility of cavity nucleation is investigated. The three most likely mechanisms by which cascade nucleation might occur are considered. Firstly, helium atoms that are present within the cascade may succeed in preventing the collapse of cascades into dislocation loops. Secondly, helium atoms in the cascades may be swept together during the cooling of the cascade to form cavity embryos. Thirdly, more distant helium atoms may be able to reach an uncollapsed vacancy aggregate in a cascade by diffusion before thermal annealing of the cascade.

ISSN:1042-0150    

DOI:10.1080/10420159008213064

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The point defect production in collision cascades causes fluctuations of vacancy and interstitial concentrations. These fluctuations are shown to affect the void growth kinetics in irradiated metals. In the present paper the analysis of the void distribution behaviour as a function of void sizes is considered. Remarkable changes in void kinetics can exist when the dislocation density is comparatively small. Under conditions determined in the present paper, the cascade induced fluctuations of the void growth rate lead to some decrease in the void density in irradiated metals. Moreover, the spatially inhomogeneous void shrinkage prevails over the homogeneous one.

ISSN:1042-0150    

DOI:10.1080/10420159008213065

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Recent investigations of helium-implanted and proton irradiated metals at medium temperatures (T≤100°C) have demonstrated the importance of high energy cascade effects for the microstructural evolution. They can effect the formation and the evolution of He densities in small bubbles formed by He implantation and are important also for the formation of periodic walls of defect clusters, a phenomenon observed under proton irradiations. Experimental results obtained by transmission electron microscopy and differential dilatometry for MeV irradiations of Cu and Ni are summarized and compared with observations after heavy-ion and neutron irradiations.

ISSN:1042-0150    

DOI:10.1080/10420159008213066

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Microstructural evolution in neutron irradiated austenitic stainless steels and Cr-Mo ferritic steels is reviewed. Important highlights are: (1) there is a strong correlation between precipitation and void evolution in austenitic steels; (2) helium affects precipitate evolution in austenitic steels, but observations indicate no effect on precipitation in ferritic steels; (3) helium has a pronounced effect on the cavity evolution of the two steel types. Helium effects are explained in terms of the interrelationship between microstructural evolution and point-defect annihilation processes. In stainless steel, three relative regimes of microstructural behavior for different helium generation rate-displacement rate ratios are recognized: (1) “low” He/dpa ratio, where helium effects on the radiation-induced microstructural evolution are negligible or develop slowly, (2) “medium” He/dpa ratio, where helium effects strongly enhance the microstructural changes, and (3) “high” He/dpa ratio, where helium effects are limited to the early development of a high density of fine bubbles which interfere with other radiation-induced microstructural changes, but allow enhanced thermal microstructural evolution to take place instead. The extensive data on austenitic steels fall within these regimes. Ferritic steels are known to be highly resistant to void swelling without helium. It is suggested that enhanced cavity formation due to helium in ferritic steels makes higher swelling a potential concern for fusion reactor applications.

ISSN:1042-0150    

DOI:10.1080/10420159008213067

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The application to fusion environments of materials data derived from fission reactors involves considerations related not only to neutron spectra but also the often dominant effect of displacement rate. It is shown in this paper that fission-fusion correlation experiments directed toward helium effects and PKA recoil spectra are frequently difficult to interpret due to the strong influences of displacement rate, low energy recoils from thermal neutron absorption and in some cases a large influence of solid transmutants. It is also shown that materials data published in earlier decades must be reevaluated in light of recent advances in defining irradiation parameters.

ISSN:1042-0150    

DOI:10.1080/10420159008213068

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159008213069

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor