The strength and damage are mutually exclusive in most alloys. It is still a challenge to understand the role of microstructural features in affecting strength and damage tolerance simultaneously. In this study, we provide a general approach to unveil the micromechanism of strength and damage trade-off in second-phase reinforced alloy. Concretely, a microstructure-based constitutive model incorporating the strain gradient plasticity theory is developed to evaluate the overall mechanical behavior and local deformation behavior of particle-reinforced alloys by finite element simulations. The strain gradient effect exacerbates the non-uniform stress distribution, particularly enhancing the local stress level around the particle-matrix interface, thereby improving the total strain hardening of the alloys. Importantly, the strain gradient effect can significantly expand regions with local stress levels surpassing the critical stress for microcrack nucleation, ultimately leading to damage initiation and failure. This elucidates the micromechanism underpinning the trade-off between strength and damage. By revealing the competitive relationship between local stress concentration and microcrack nucleation stress, the comprehensive effects of particle size and volume fraction on the strength, strain hardening and damage tolerance are quantitatively predicted. It is recommended to adjust the particle volume fraction based on reducing the particle size to obtain the desired properties. The present work discerns the inherent origin of the strength-damage trade-off in particle-reinforced alloy and sheds light on the role of the particle size and volume fraction on the strength and damage tolerance, which can offer valuable guidance for developing high-performance particle-reinforced materials.

中文翻译：

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基于应变梯度塑性理论的第二相强化合金强度与损伤权衡的微观机制

大多数合金的强度和损伤是相互排斥的。了解微观结构特征在同时影响强度和损伤容限方面的作用仍然是一个挑战。在这项研究中，我们提供了一种通用方法来揭示第二相增强合金的强度和损伤权衡的微观机制。具体而言，开发了一种结合应变梯度塑性理论的基于微观结构的本构模型，通过有限元模拟评估颗粒强化合金的整体力学行为和局部变形行为。应变梯度效应加剧了应力分布的不均匀性，特别是提高了颗粒-基体界面周围的局部应力水平，从而提高了合金的总应变硬化。重要的是，应变梯度效应可以显着扩大局部应力水平超过微裂纹成核临界应力的区域，最终导致损伤萌生和失效。这阐明了支撑强度和损伤之间权衡的微观机制。通过揭示局部应力集中与微裂纹形核应力之间的竞争关系，定量预测了颗粒尺寸和体积分数对强度、应变硬化和损伤容限的综合影响。建议在减小粒径的基础上调整颗粒体积分数以获得所需的性能。目前的工作揭示了颗粒增强合金强度与损伤权衡的内在根源，并阐明了颗粒尺寸和体积分数对强度和损伤容限的作用，这可以为开发高性能合金提供有价值的指导颗粒增强材料。