ANNIHILATION OF DISLOCATIONS DURING TENSILE AND CYCLIC DEFORMATION AND LIMITS OF DISLOCATION DENSITIES
ANNIHILATION OF DISLOCATIONS DURING TENSILE AND CYCLIC DEFORMATION AND LIMITS OF DISLOCATION DENSITIES
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DOI：
10.1080/01418617908234871
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发表时间：
1979-01-01
期刊：
影响因子：
--
通讯作者：
MUGHRABI, H
中科院分区：
文献类型：
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作者：
ESSMANN, U;MUGHRABI, H
有人建议，在低温下的位错滑移，无论是螺旋和非螺旋位错相互湮灭的相反符号的位错接近紧密相邻的滑移面。实验证据进行了总结，并讨论了可能的机制。考虑位错的湮灭，建立了形变过程中位错积累的唯象模型。和BC。金属晶体表明，在应变硬化期间发生刃位错和/或螺位错的湮灭，并可导致稳态变形。由此可见，在变形过程中引入的位错密度不能超过明确定义的上限，该上限明显低于静态情况下估计的假设上限。观测结果表明，螺位错湮灭的临界位错对间距为0.50 -500 nm，刃位错为0.16 nm（铜）。由非螺位错湮灭形成的点缺陷的原子浓度在大多数情况下都很低（0.10 −3）。然而，可以得出结论，在疲劳铜中持久Blip带的富位错壁中，存在相当高浓度的点缺陷（Δ 10−3）。
It is proposed that, during dislocation glide at low temperatures, both screw and non-screw dislocations annihilate mutually with dislocations of opposite sign approaching on closely neighbouring glide planes. The experimental evidence is summarized and possible mechanisms are discussed. Phenomenological models of dislocation accumulation during deformation, taking into account the annihilation of dislocations, are formulated.The analysis of selected examples of tensile and cyclic deformation of f.c.c. and b.c.c. metal crystals demonstrates that annihilation of edge and/or screw dislocations occurs during strain hardening and can lead to steady state deformation. It follows that the dislocation densities introduced during deformation cannot exceed well-defined upper limits that are distinctly lower than the hypothetical upper limits estimated for the static case. The observations suggest that the critical spacings of dislocation pairs that annihilate are ∼.50–500 nm for screw and ∼ 1·6 nm for edge dislocations (in copper).The atomic concentration of point defects formed by the annihilation of non-screw dislocations is found to be low in most cases (∼10−3). However, it is concluded that, in the dislocation–rich walls of persistent Blip bands in fatigued copper, a rather high concentration of point defects prevails (∼10−3).