多形状障碍物硬化的位错动力学计算及统一硬化模型推导

UNIFIED HARDENING MODEL AND DISLOCATION DYNAMICS ANALYSIS FOR MULTI-SHAPE OBSTACLE HARDENING

  • 摘要: 位错与辐照缺陷的相互作用会导致材料屈服强度上升,引起材料的辐照硬化。针对任意形状不可穿过缺陷引起的硬化,本文提出了一种统一形式的临界剪切应力预测模型。文章首先综述了现有研究中常见的球形障碍物硬化模型(Bacon-Kocks-Scattergood模型),并讨论了这些模型在处理复杂形状障碍物时的局限性。随后,通过位错动力学模拟与线弹性理论推导,研究了位错与不同形状障碍物(包括球形、椭球形和正方体)的相互作用规律,提出了基于几何构型的统一硬化预测公式。结果表明,该线弹性模型的预测值与位错动力学计算结果吻合度较高,并能较好的预测不同形状障碍物的耦合硬化效应。研究对改进现有硬化模型及提升辐照材料性能预测精度具有重要意义。

     

    Abstract: This study aims to develop a unified model for predicting the critical resolved shear stress (CRSS) in materials containing impenetrable obstacles of arbitrary shapes, which is essential for understanding radiation hardening. The interaction between dislocations and radiation-induced defects, such as voids, bubbles, and dislocation loops, leads to an increase in material yield strength, a phenomenon known as radiation hardening. Traditional models, such as the Bacon-Kocks-Scattergood (BKS) model, are limited to spherical obstacles and fail to accurately predict the hardening effects of complex-shaped defects. To address this limitation, we propose a generalized hardening model based on linear elasticity theory, which accounts for the geometric configuration of obstacles and provides a unified framework for predicting CRSS. The research methodology combines dislocation dynamics simulations and theoretical derivations to investigate the interaction mechanisms between dislocations and obstacles of various shapes, including spherical, ellipsoidal, and cubic geometries. The proposed model is validated through extensive simulations, demonstrating its ability to predict CRSS with high accuracy across different obstacle shapes. The results show that the model effectively captures the coupled hardening effects of multiple obstacles with varying geometries and strengths. Key findings include: (1) The proposed unified model extends the traditional BKS framework by incorporating critical debonding angles, enabling accurate predictions for non-spherical obstacles. (2) Dislocation dynamics simulations reveal that the hardening process is influenced by the geometric arrangement of obstacles, with the critical stress being inversely proportional to the spacing between obstacles. (3) When dislocations interact with multiple obstacles of different shapes, the overall hardening effect can be approximated by the average of the individual hardening contributions. The study also highlights the limitations of existing models in dealing with complex-shaped obstacles, such as needle-like precipitates in tungsten and square-shaped precipitates in Ni-based alloys. By considering the geometric configuration of obstacles, the proposed model provides a more accurate prediction of CRSS for materials with irregularly shaped defects. The results of dislocation dynamics simulations confirm that the model can effectively predict the hardening effects of spherical, ellipsoidal, and cubic obstacles, as well as their combined effects. In conclusion, this study provides a robust theoretical tool for predicting the hardening effects of complex-shaped obstacles, offering significant insights for improving the design and performance prediction of radiation-resistant materials. The proposed model has practical implications for optimizing material properties in nuclear engineering and other high-radiation environments. By extending the traditional BKS model to account for the geometric configuration of obstacles, this research contributes to a deeper understanding of the interaction between dislocations and radiation-induced defects, ultimately enhancing the accuracy of material performance predictions in real-world applications.

     

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