Monotonic tensile and cyclic deformation behaviours are investigated under different microstructural rafting states of a SC Ni-based superalloy, with emphasis on the influences of the rafting extent, type and loading orientation. The deformed microstructures and the dislocation configurations are characterized to give a micro-based understanding on the varying of deformation behaviours due to rafting. It is found that the decreases in the initial yield point and cyclic stress amplitude are only related to the rafting extent. Nevertheless, the rafting type (namely, the plate-like and needle-like morphology) has an undeniable contribution to the shape of hysteresis loops, where the plate-like rafting morphology results in more significant Bauschinger effect than needle-like rafting morphology. The variation of monotonic and cyclic deformation induced by rafting shares affinity with the alteration of internal stress and the movement of dislocations. Afterwards, a microstructure-sensitive constitutive model with two-phase flow rules has been developed. The effect of rafting on the monotonic and cyclic stress-strain responses is captured by introduce a series of microscopic mechanisms and a micromechanics-based back stress model that considers the morphology and size of the γ'/γ two-phase structures. The developed model is used to simulate the macroscopic stress-strain responses of the SC Ni-based superalloy under different rafting states. Model predictions are in good agreement with tests, capturing the reduction of cyclic stress amplitudes and the change in hysteresis loops. Finally, the impacts of the two-phase flow rules and the micromechanics-based back stress on the simulation capability have been discussed.

中文翻译：

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具有各向异性微观结构漂流图案的镍基单晶高温合金在高温下的单调拉伸和循环变形：实验和本构建模


研究了 SC 镍基高温合金在不同微观结构漂流状态下的单调拉伸和循环变形行为，重点研究了漂流程度、类型和加载方向的影响。变形的微观结构和位错配置的特征在于对由于漂流引起的变形行为的变化提供基于微观的理解。研究发现，初始屈服点和循环应力幅的降低仅与漂流程度有关。然而，漂流类型（即板状和针状形态）对磁滞回线的形状具有不可否认的贡献，其中板状漂流形态比针状漂流形态产生更显着的包辛格效应。漂流引起的单调和循环变形的变化与内应力的变化和位错的运动有着密切的关系。随后，开发了具有两相流规则的微观结构敏感本构模型。通过引入一系列微观机制和考虑 γ'/γ 两相结构的形态和尺寸的基于微观力学的反应力模型，捕获了漂流对单调和循环应力-应变响应的影响。所开发的模型用于模拟 SC 镍基高温合金在不同漂流状态下的宏观应力应变响应。模型预测与测试非常吻合，捕捉到了循环应力幅值的减小和磁滞回线的变化。最后，讨论了两相流规则和基于微观力学的反应力对模拟能力的影响。