Finite element simulations of microvoid growth due to selective oxidation in binary alloys
Finite element simulations of microvoid growth due to selective oxidation in binary alloys
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DOI：
10.1088/0965-0393/14/7/009
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发表时间：
2006-10
影响因子：
1.8
通讯作者：
S. Pal;D. Kubair
中科院分区：
文献类型：
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作者：
S. Pal;D. Kubair
在燃气轮机中使用的热障涂层系统中观察到选择性氧化引起的空隙生长。这些空隙出现在粘合层 (BC) 和热生长氧化物 (TGO) 层之间的界面处。在本文中，我们开发了建模框架来模拟二元合金中由于耦合扩散和蠕变而导致的微孔生长。我们已将建模框架实施到现有的有限元程序中。开发的建模框架和程序用于模拟二元 β-NiAl 合金中选择性氧化驱动的微孔生长。模拟了由于相互扩散和蠕变的共同作用而导致的轴对称空隙生长。在我们的研究中，空隙的锐度和蠕变方向被视为参数。我们的模拟表明，当在所有方向上蠕变的可能性相同（各向同性）时，空隙会膨胀，但形状不会发生任何变化。当蠕变仅限于沿径向和切向发生时，可以预测与实验中观察到的空洞生长模式类似。与尖锐的空洞相比，半球形空洞的增长速度更快。在尖锐空洞的情况下，锐度会增加，并可能导致与相邻空洞的相互作用，从而导致实验中观察到的 TGO 层散裂。
Selective oxidation induced void growth is observed in thermal barrier coating systems used in gas turbines. These voids occur at the interface between the bond coat (BC) and the thermally grown oxide (TGO) layer. In this paper we develop the modelling framework to simulate microvoid growth due to coupled diffusion and creeping in binary alloys. We have implemented the modelling framework into an existing finite element programme. The developed modelling framework and programme is used to simulate microvoid growth driven by selective oxidation in a binary β-NiAl alloy. Axisymmetric void growth due to the combined action of interdiffusion and creeping is simulated. The sharpness of the void and direction of creeping are considered as parameters in our study. Our simulations show that the voids dilate without any change in shape when creeping is equally likely in all the directions (isotropic). Void growth patterns similar to those observed in experiments are predicted when the creeping is restricted to occur only along the radial and tangential directions. A hemispherical void grows faster compared to a sharp void. The sharpness increases in the case of a sharp void and could lead to interactions with the neighbouring voids leading to spallation of the TGO layer as observed in experiments.