Precipitates contribute significantly to the strength of many common engineering aluminum alloys. The stress orienting effect of disk-shaped θ′ precipitates in Al-Cu alloy may lead to varying orientation distribution of the precipitates and, thus, varying critical resolved shear stress (CRSS) and macroscopic mechanical properties. In this work, θ′ precipitates was incorporated into discrete dislocation dynamics (DDD) simulation software ParaDiS. This approach was applied to systematically investigate how CRSS is affected by the orientation distribution and spatial distribution of the θ′ precipitates which has a considerable effect on the CRSS but has received less attention in previous research. As a simplification, the orientation distribution of a one-dimensional equidistantly distributed sequence of precipitates are taken as the research object. By varying the orientation of each precipitate, DDD simulations with wide range of overall orientation distributions can be obtained. Based on this, we propose an orientation factor that can adequately define the relationship between the orientation distribution and the CRSS. A modified Orowan model considering orientation distribution with parameters calibrated by dislocation dynamics simulations is suggested in light of these investigations, enabling rapid prediction of CRSS. Subsequently, the spatial distribution of precipitates was described using the extreme distribution, and a spatial factor was created by examining the mean and variance. This model was extended to the case of complex precipitate distributions by considering the spatial factor. The accuracy of the extended model was verified through DDD simulation results for randomly distributed precipitates and the prediction accuracy was greatly improved. This work makes it possible to calculate precipitation strengthening in Al-Cu alloys quantitatively and precisely while accounting for specific orientation distribution and spatial distribution.

中文翻译：

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考虑取向和空间分布，θ′ 在 Al-Cu 合金中沉淀强化：离散位错动力学研究

析出物对许多常见工程铝合金的强度有显着贡献。 Al-Cu合金中盘状θ'析出物的应力取向效应可能导致析出物的取向分布变化，从而改变临界分辨剪切应力（CRSS）和宏观力学性能。在这项工作中，θ′析出物被纳入离散位错动力学（DDD）模拟软件ParaDiS中。该方法用于系统地研究CRSS如何受到θ′析出物的取向分布和空间分布的影响，这对CRSS有相当大的影响，但在先前的研究中较少受到关注。作为简化，以一维等距分布的析出物序列的取向分布为研究对象。通过改变每个沉淀物的取向，可以获得具有广泛总体取向分布的 DDD 模拟。基于此，我们提出了一个方向因子，可以充分定义方向分​​布与 CRSS 之间的关系。根据这些研究，提出了一种修改后的 Orowan 模型，该模型考虑了取向分布，并通过位错动力学模拟校准了参数，从而能够快速预测 CRSS。随后，使用极值分布描述析出物的空间分布，并通过检查均值和方差创建空间因子。通过考虑空间因素，将该模型扩展到复杂沉淀物分布的情况。通过随机分布析出物的DDD模拟结果验证了扩展模型的准确性，预测精度大大提高。这项工作使得定量、精确地计算 Al-Cu 合金中的沉淀强化成为可能，同时考虑了特定的取向分布和空间分布。