Acoustic study of kinetics of vacancy diffusion toward dislocations in aluminum
Acoustic study of kinetics of vacancy diffusion toward dislocations in aluminum
复制标题
铝中空位扩散至位错动力学的声学研究
DOI：
10.1016/j.actamat.2004.10.007
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发表时间：
2005
期刊：
影响因子：
9.4
通讯作者：
M. Hirao
中科院分区：
文献类型：
--
作者：
H. Ogi;A. Tsujimoto;S. Nishimura;M. Hirao
利用超声横波，研究了铝中空位向位错迁移的动力学。超声衰减对有效位错长度敏感，有效位错长度因点缺陷的偏析而缩短。主要进行了两个测量：(I)测量了弹性变形后衰减行为的温度依赖性；(Ii)连续测量了从573K淬火到冷水再到液氮温度的衰减。样品为多晶铝和单晶铝，纯度为99.995%。前者通过Granato-Hikata-Lücke理论为我们提供了主导点缺陷迁移的激活能0.28 eV。后者的测量揭示了空位的动力学：衰减系数在125和250K时迅速下降两倍，对应的迁移激活能分别为0.28和0.61 eV。因此，弹性变形后的衰减变化与125K淬火后的衰减变化是相同的机理。我们将0.28 eV的迁移归因于空位沿位错的快速扩散。0.61 eV的迁移与空位在铝中的整体扩散相一致。在整个研究过程中，使用了电磁声谐振法进行非接触式和高精度的衰减测量。
Using ultrasonic shear waves, we study the kinetics of migration of vacancy to dislocations in aluminum. Ultrasonic attenuation is sensitive to the effective dislocation length, which is shortened by the segregation of point defects. Two principal measurements were done: (i) measurement of temperature dependence of decay behavior of attenuation after elastic deformation; (ii) continuous measurement of attenuation of a specimen quenched from 573 K to cold-water and then to liquid-nitrogen temperatures. The specimens were polycrystalline and monocrystal aluminum with 99.995% purity. The former measurement provided us with the activation energy 0.28 eV for migration of dominant point defects through the Granato–Hikata–Lücke theory. The latter measurement informed us of the kinetics of vacancy: the attenuation coefficient rapidly decreased twice at 125 and 250 K, corresponding to activation energies 0.28 and 0.61 eV for migration, respectively. Thus, the same mechanism occurs for the attenuation change after elastic deformation and at 125 K after quenching. We attributed the 0.28-eV migration as fast diffusion of vacancy along dislocations. The 0.61-eV migration is consistent with the bulk diffusion of vacancy in aluminum. Throughout this study, the electromagnetic acoustic resonance method was used for making noncontacting and highly accurate measurement of attenuation.