Meixner Felix, Ahmadi Mohammad Reza, Sommitsch Christof
Institute of Materials Science, Joining and Forming, Graz University of Technology, Kopernikusgasse 24/1, 8010 Graz, Austria.
Materials (Basel). 2022 Feb 17;15(4):1495. doi: 10.3390/ma15041495.
The number of fossil fueled power plants in electricity generation is still rising, making improvements to their efficiency essential. The development of new materials to withstand the higher service temperatures and pressures of newer, more efficient power plants is greatly aided by physics-based models, which can simulate the microstructural processes leading to their eventual failure. In this work, such a model is developed from classical nucleation theory and diffusion driven growth from vacancy condensation. This model predicts the shape and distribution of cavities which nucleate almost exclusively at grain boundaries during high temperature creep. Cavity radii, number density and phase fraction are validated quantitively against specimens of nickel-based alloys (617 and 625) tested at 700 °C and stresses between 160 and 185 MPa. The model's results agree well with the experimental results. However, they fail to represent the complex interlinking of cavities which occurs in tertiary creep.
用于发电的化石燃料发电厂数量仍在增加，因此提高其效率至关重要。基于物理的模型极大地推动了新型材料的开发，这些材料能够承受更新的、更高效发电厂更高的服役温度和压力，该模型可以模拟导致材料最终失效的微观结构过程。在这项工作中，基于经典成核理论和空位凝聚的扩散驱动生长建立了这样一个模型。该模型预测了在高温蠕变过程中几乎完全在晶界处形核的空洞的形状和分布。针对在700°C以及160至185MPa应力下测试的镍基合金（617和625）试样，对空洞半径、数密度和相分数进行了定量验证。模型结果与实验结果吻合良好。然而，它们未能体现出在第三阶段蠕变中出现的空洞复杂的相互连接情况。
