Helium bubbles in nickel annealed at T>0.7Tm

被引:35
|
作者
Chernikov, VN
Trinkaus, H
Ullmaier, H
机构
[1] Forschungszentrum Julich, Inst Festkorperforsch, D-52425 Julich, Germany
[2] Russian Acad Sci, Inst Phys Chem, Moscow 117915, Russia
[3] EURATOM, KFA, Julich, Germany
基金
俄罗斯基础研究基金会;
关键词
D O I
10.1016/S0022-3115(97)00275-4
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Helium-induced cavities in fusion materials are considered to be detrimental. Valuable information on He bubbles and on the basic mechanisms underlying their evolution is obtained by post-implantation annealing, subsequent to He implantation at about 300 K. For Ni and Cu, it has been shown that up to annealing temperatures T-a less than or equal to 0.7T(m) (T-m is the melting point), highly overpressurized bubbles form in the volume and coarsen very slowly by migration and coalescence, whereas near vacancy sources the overpressure relaxes and the coarsening occurs rapidly by Ostwald ripening (OR) which leads to the appearance of small and large He cavities. Annealing of He loaded Ni at T-a from 0.72T(m) to 0.92T(m) leads to the formation of only one population of nearly equilibrium bubbles which is related to the recovery of the ability of dislocations to emit vacancies into their surroundings. The effective activation energy of the increase of the mean bubble radius was found to be 0.60 +/- 0.02 eV, which is lower than that for the OR at lower temperatures (1.1 eV). Analysis shows that the mechanism covering the coarsening of He bubbles at very high temperatures is still OR, but limited by the rate of ledge nucleation on the bubble walls. (C) 1997 Elsevier Science B.V.
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页码:103 / 110
页数:8
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