Modeling of Oxygen Diffusion Along Grain Boundaries in a Nickel-Based Superalloy
Modeling of Oxygen Diffusion Along Grain Boundaries in a Nickel-Based Superalloy
复制标题
镍基高温合金中氧沿晶界扩散的模拟
DOI：
10.1115/1.4003777
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Zhao L
中科院分区：
文献类型：
--
作者：
Zhao L
对一种多晶镍基高温合金进行了晶级氧扩散的有限元分析，旨在量化高温下表面氧化条件下的氧化损伤。有限元模型中显式考虑了晶界组织，晶界是氧扩散的主要途径。用该模型模拟了氧在和温度之间的自然扩散，该温度受抛物线氧化速率和氧扩散系数的控制。为了研究机械应力对氧扩散的影响，使用子模型技术对蠕变加载条件下的一般试件几何形状进行了顺序耦合变形-扩散分析。材料的本构行为分别由晶界塑性模型和整体粘塑性模型描述。应力辅助氧扩散是由压力因子表示的静水应力梯度驱动的。晶级上的非均匀变形对氧的扩散有很大影响，导致氧进一步渗透到块体材料中。增加负载水平和温度可提高材料中的氧浓度和渗透率。在以下情况下，机械负荷对氧渗透的影响似乎可以忽略不计，因为氧扩散系数和压力因子值极低。在存在表面微裂纹的情况下，由于裂纹尖端附近存在较高的应力水平，氧倾向于聚集在裂纹尖端周围，导致材料的局部脆化，促进裂纹的快速扩展。
Finite element analyses of oxygen diffusion at the grain level have been carried out for a polycrystalline nickel-based superalloy, aiming to quantify the oxidation damage under surface oxidation conditions at high temperature. Grain microstructures were considered explicitly in the finite element model where the grain boundary was taken as the primary path for oxygen diffusion. The model has been used to simulate natural diffusion of oxygen at temperatures betweenand, which are controlled by the parabolic oxidation rate and oxygen diffusivity. To study the effects of mechanical stress on oxygen diffusion, a sequentially coupled deformation-diffusion analysis was carried out for a generic specimen geometry under creep loading condition using a submodeling technique. The material constitutive behavior was described by a crystal plasticity model at the grain level and a unified viscoplasticity model at the global level, respectively. The stress-assisted oxygen diffusion was driven by the gradient of hydrostatic stress in terms of pressure factor. Heterogeneous deformation presented at the grain level imposes a great influence on oxygen diffusion atand above, leading to further penetration of oxygen into the bulk material. Increased load level and temperature enhance oxygen concentration and penetration within the material. Atand below, mechanical loading seems to have negligible influence on the oxygen penetration because of the extremely low values of oxygen diffusivity and pressure factor. In the case of an existing surface microcrack, oxygen tends to accumulate around the crack tip due to the high stress level presented near the crack tip, leading to localized material embrittlement and promotion of rapid crack propagation.
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DOI：
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发表时间：
1982
期刊：
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DOI：
--
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DOI：
--
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期刊：
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F. L. Carranza;R. Haber
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DOI：
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发表时间：
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影响因子：
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DOI：
--
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