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Nucleation Process of Voids Studied by Positron Lifetime Spectroscopy

正电子寿命谱研究空洞成核过程

基本信息

批准号：
60550459
负责人：
SHIRAI Yasuharu
金额：
$ 1.22万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550459/
关键词：
Void Hydrogen Aluminium Positron 空孔

项目摘要

In order to clarify the void formation mechanism by hydrogen in aluminium, positron lifetime study has been performed on pure Al, and on dilute Al-Mg, Al-Si and Al-Ag alloys. The main results are summarized as follows.1. Hydrogen were introduced into pure Al(99.9999%) specimens by four different methods (1)quenching from hydrogen atmosphere,(2)quenching into hydrochloric acid,(3)glow discharge in hygrogen gas after quenching into brine and (4)electrolysis after quenching into brine. In all cases void formation were observed during subsequent isochronal annealing.2. It has been found that the hydrogen introduction before or during quenching is much more effective than after quenching on void formation. Furthermore, in the case of hydrogen charge arter quenching, the ratio of the void formation to faulted dislocation fromation increases with decreasing quenching temperature. These results strongly suggest that hydrogen has the effect on void nucleation only at the very early stage in vacancy clustering.3. With the aid of computer simulations of vacancy kinetics during quenching, a nucleation model for the secondary defects is proposed: Without a hydrogen atom trivacancies and tetravacancies are attended with great atomic relaxations and grow into faulted dislocation loops. On the other hand, with hydrogen atoms trivacancies and tetravacancies cannot have the relaxed configulations and act as void nuclei.4. No indication of void formation has been observed for dilute Al-Mg,Al-Si and Al-Ag alloys hydrogen charged. This result indicates that these solute atoms trap hydrogen and inhibit the nucleation of voids mentioned above.5. It has been found that the density of voids formed in 5N Al is always lower than that in 6N Al. This clearly shows that even such a small amount of impurities as 10ppm suppress the void formation by hydrogen.

为了阐明氢在铝中形成空穴的机制，对纯铝、稀铝镁合金、铝硅合金和铝银合金进行了正电子寿命研究。主要研究结果总结如下：1.研究成果。用四种不同的方法(1)在氢气中淬火，(2)在盐酸中淬火，(3)在盐水中淬火后在氢气中辉光放电，(4)在盐水中淬火后电解，将氢引入纯铝(99.9999%)中。在所有情况下，在随后的等时退火过程中都观察到了空洞的形成。研究发现，在淬火前或淬火过程中引入氢对空洞形成的影响要比淬火后大得多。此外，在氢气充氢后淬火的情况下，空洞形成与断层位错形成的比率随着淬火温度的降低而增加。这些结果有力地表明，氢只在空位聚集的非常早期阶段对空位形核有影响。借助于计算机模拟淬火过程中的空位动力学，提出了二次缺陷的形核模型：在无氢原子的情况下，三空位和四空位伴随着较大的原子驰豫，并生长成断层位错环。另一方面，对于氢原子，三位空位和四位空位不能具有松弛构型并起到空位核的作用。未观察到充氢的稀铝镁、铝硅和铝银合金有空洞形成的迹象。这一结果表明，这些溶质原子捕获了氢，并抑制了上述空位的形核。结果表明，5N Al中形成的空洞密度始终低于6N Al。这清楚地表明，即使是如此少量的杂质，如10ppm，也抑制了氢形成的空穴。