Abstract Formation of raft structure and widening of γ matrix width are usually observed in the nickel-based single crystal superalloys at high temperature loading conditions. But the effect of this rafting behavior on the mechanical property is still ambiguous until now. In the present study, a visco-plasticity phase-field model that based on the classical flow theory and the creep theory is developed to investigate the mechanical property and rafting behavior of nickel-based superalloys. The relationship between the yield stress and γ matrix width is firstly paid attention through a series of tensile tests. Simulations that have considered the effect of Orowan stress indicate that the yield stress of γ′/γ microstructures decreases with the increase of γ matrix width. When the matrix width exceeds to a critical value, the yield stress of the microstructure becomes constant. The presence of the yield stage during the tensile process is related to the active slip systems shearing into γ′ precipitates. Then a damage law is introduced to assess the creep resistance of the material. Our simulations precisely predict the creep life and present the shape of strain curves. The evolution rule of strain curves is revealed by analyzing the distribution of plastic strain field and equivalent stress field. Furthermore, simulations that consider four γ′ variants and only one γ′ variant are compared. Results indicate that a stable raft structure can enhance the creep resistance of the superalloys.

中文翻译：

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镍基高温合金力学性能和漂流行为的粘塑性相场模拟

摘要 镍基单晶高温合金在高温加载条件下通常会形成筏板结构和γ基体宽度变宽。但直到现在，这种漂流行为对机械性能的影响仍然不明确。在本研究中，建立了基于经典流动理论和蠕变理论的粘塑性相场模型，以研究镍基高温合金的力学性能和漂流行为。通过一系列拉伸试验首先关注屈服应力与γ基体宽度之间的关系。考虑Orowan应力影响的模拟表明，γ'/γ显微组织的屈服应力随着γ基体宽度的增加而降低。当矩阵宽度超过临界值时，微观结构的屈服应力变得恒定。拉伸过程中屈服阶段的存在与剪切成γ'沉淀的活性滑移系统有关。然后引入损伤定律来评估材料的抗蠕变性。我们的模拟精确预测蠕变寿命并呈现应变曲线的形状。通过分析塑性应变场和等效应力场的分布，揭示应变曲线的演化规律。此外，比较了考虑四种 γ' 变体和仅一种 γ' 变体的模拟。结果表明，稳定的筏板结构可以提高高温合金的抗蠕变性。然后引入损伤定律来评估材料的抗蠕变性。我们的模拟精确预测蠕变寿命并呈现应变曲线的形状。通过分析塑性应变场和等效应力场的分布，揭示应变曲线的演化规律。此外，比较了考虑四种 γ' 变体和仅一种 γ' 变体的模拟。结果表明，稳定的筏板结构可以提高高温合金的抗蠕变性。然后引入损伤定律来评估材料的抗蠕变性。我们的模拟精确预测蠕变寿命并呈现应变曲线的形状。通过分析塑性应变场和等效应力场的分布，揭示应变曲线的演化规律。此外，比较了考虑四种 γ' 变体和仅一种 γ' 变体的模拟。结果表明，稳定的筏板结构可以提高高温合金的抗蠕变性。