ISSN:
1432-0630
Schlagwort(e):
76.80
;
61.10.Fr
;
23.40
;
61.70.−r
;
62.20.Fe
;
61.70.Tm
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract In previous Perturbed-Angular-Correlation (PAC) studies of the γ-γ emission of 111In probe nuclei in cold-worked or particle-irradiated nickel, it has been found that thermal annealing in the temperature regime of recovery stage III leads to the formation of so-called C-defects (Cubic defects). This is indicated by the occurrence of a new frequency of about 80 Mrad/s, in addition to the frequency (≈200 Mrad/s) that is due to 111In on substitutional sites. Obviously, the C-defects are complexes consisting of 111In and the intrinsic point-defect species that migrates freely in recovery stage III. Therefore, they have played an important rôle in the long-standing controversy on whether the recovery-stage-III defects are vacancies (one-interstitial model) or self-interstitials (two-interstitial model). The present paper reports on a novel experimental effort to reveal the nature of the C-defects by combining PAC studies on nickel samples differently pretreated in a systematic way, investigations of the Extended X-ray Absorption Fine Structure (EXAFS) on In-doped nickel, and measurements of the decay rate of 111In nuclei in the Electron-Capture-Induced Decay (ECID). On the basis of the results of these experiments it is concluded that the defects trapped by substitutional 111In atoms (Ins) in recovery stage III are self-interstitials (I), as expected according to the two-interstitial model. Moreover, there is evidence that the C-defects are In interstitials on tetrahedral sites (Ini) that form exclusively in the vicinity of the specimen surface from Ins − I pairs via the reaction Ins+I → Ini.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00331710
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