A theory of dislocation cell formation based on stochastic dislocation dynamics
A theory of dislocation cell formation based on stochastic dislocation dynamics
复制标题
DOI：
10.1016/1359-6454(95)00364-9
复制
发表时间：
1996-06
期刊：
影响因子：
9.4
通讯作者：
P. Hähner
中科院分区：
文献类型：
--
作者：
P. Hähner
发展了一种随机有效介质理论，该理论解释了动态位错相互作用引起的局部应力和应变率的几何必要波动。将这一概念应用于多次滑移中位错晶胞的形成。从总位错密度ϱ的朗之万型演化方程出发，导出了相应的概率分布PS(ϱ)的福克-普朗克方程。细胞形成与噪声诱导的与PS(ϱ)质变相关的非平衡相变有关。发现晶胞大小与流动应力(相似原理)成反比。讨论了细胞形成的临界条件和交叉滑移在细胞形成中的作用。
A stochastic effective medium theory is developed that accounts for the geometrically necessary fluctuations of the local stress and strain rate resulting from dynamic dislocation interactions. The concept is applied to the formation of dislocation cells in multiple slip. Starting from a Langevin-type evolution equation for the total dislocation density ϱ, a corresponding Fokker-Planck equation for the probability distribution ps(ϱ) is derived. Cell formation is related to a noise-induced non-equilibrium phase transition associated with a qualitative change of ps(ϱ). The cell size is found to be in inverse proportion to the flow stress (principle of similitude). Critical conditions for, and the role of cross slip in, cell formation are discussed.