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首页> 外文期刊>Physical review, B >Instability of dislocation fluxes in a single slip: Deterministic and stochastic models of dislocation patterning
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Instability of dislocation fluxes in a single slip: Deterministic and stochastic models of dislocation patterning

机译：单滑移中位错通量的不稳定性：脱位图案化的确定性和随机模型

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摘要

We study a continuum model of dislocation transport in order to investigate the formation of heterogeneous dislocation patterns. We propose a physical mechanism that relates the formation of heterogeneous patterns with a well-defined wavelength to the stress-driven dynamics of dislocation densities that tries to minimize the internal energy while subject to dynamic constraints and a density-dependent, friction-like flow stress. This leads us to an interpretation that resolves the old "energetic vs dynamic" controversy regarding the physical origin of dislocation patterns and emphasizes the hydrodynamic nature of the instability that leads to dislocation patterning, which we identify as an instability of dislocation transport that is not dependent on processes such as dislocation multiplication or annihilation. We demonstrate the robustness of the developed patterning scenario by considering the simplest possible case (plane strain, single slip) in two model versions that consider the same driving stresses but implement the transport of dislocations that controls dislocation density evolution in two very different manners, namely (i) a hydrodynamic formulation that considers transport equations that are continuous in space and time, assuming that the dislocation velocity depends linearly on the local driving stress, and (ii) a stochastic cellular automaton implementation that assumes spatially and temporally discrete transport of discrete "packets" of dislocation density that move according to an extremal dynamics. Despite the differences, we find that the emergent patterns in both models are mutually consistent and in agreement with the prediction of a linear stability analysis of the continuum model. We also show how different types of initial conditions lead to different intermediate evolution scenarios that, however, do not affect the properties of the fully developed patterns.
机译：我们研究了一个连续的位错运输模型，以调查异质位错模式的形成。我们提出了一种物理机制，该物理机制涉及具有明确限定的波长的异构图案的形成，其脱位密度的应力驱动的动态，其试图在受到动态约束的同时最小化内部能量和依赖于密度的摩擦力的流量应力。这导致我们解释了关于脱位模式的物理来源的旧“能量VS动态”争议，并强调导致错位图案的不稳定性的流体动力学性质，我们认为是不依赖的错位运输的不稳定性在脱位乘法或湮灭等过程中。我们通过考虑最简单的案例（平面应变，单滑）在考虑同样的驾驶应力的两个模型版本中，展示了开发的图案化场景的稳健性，但是实现了以两个非常不同的方式控制位错密度演化的脱位传输，即（i）假设位错速度在局部驾驶应力线性上线性取决于位于局部驾驶应力，并且（ii）在局部驾驶应力上线性取决于空间和时间离散传输的随机蜂窝自动机实现，其进行了一种流体动力学制剂数据包“根据极值动态移动的错位密度。尽管存在差异，但我们发现两种模型中的紧急模式都是相互一致的，并且与预测连续um模型的线性稳定性分析。我们还展示了不同类型的初始条件如何导致不同的中间进化方案，但是，不影响完全开发模式的属性。

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  • 来源
    《Physical review, B》 |2018年第5期|共15页
  • 作者

    Wu Ronghai; Tuzes Daniel; Ispanovity Peter Dusan; Groma Istvan; Hochrainer Thomas; Zaiser Michael;

  • 作者单位

    Northwestern Polytech Univ Sch Mech Civil Engn &

    Architecture Xian 710129 Shaanxi Peoples R China;

    Eotvos Lorand Univ Dept Mat Phys ELTE POB 32 H-1517 Budapest Hungary;

    Eotvos Lorand Univ Dept Mat Phys ELTE POB 32 H-1517 Budapest Hungary;

    Eotvos Lorand Univ Dept Mat Phys ELTE POB 32 H-1517 Budapest Hungary;

    Graz Univ Technol Inst Festigkeitslehre Kopemikusgasse 24-1 A-8010 Graz Austria;

    Friedrich Alexander Univ Erlangen Nurberg FAU Dept Mat Sci Inst Mat Simulat Dr Mack Str 77 D-90762 Furth Germany;

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  • 中图分类 固体物理学;
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