Papadaki Chrysanthi, Li Wei, Korsunsky Alexander M
Multi-Beam Laboratory for Engineering Microscopy (MBLEM), Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
Rolls-Royce plc, P.O. Box 31, Derby DE24 8BJ, UK.
Materials (Basel). 2018 Aug 24;11(9):1528. doi: 10.3390/ma11091528.
The ability to predict the sizes of secondary and tertiary γ' precipitate is of particular importance for the development and use of polycrystalline nickel-based superalloys in demanding applications, since the size of the precipitate exerts a strong effect on the mechanical properties. Many studies have been devoted to the development and application of sophisticated numerical models that incorporate the influence of chemical composition, concentration gradients, and interfacial properties on precipitate size and morphology. In the present study, we choose a different approach, concentrating on identifying a correlation between the mean secondary and tertiary γ' size and the cooling rate from solution treatment temperature. The data are collected using the precipitate size distribution analysis from high-resolution scanning electron microscopy. This correlation is expressed in the form of a power law, established using experimental measurement data and rationalized using a re-derivation of McLean's theory for precipitate growth, based on well-established thermodynamic principles. Specifically, McLean's model is recast to consider the effect of cooling rate. The derived model captures the correlation correctly despite its simplicity, and is able to predict the mean secondary and tertiary γ' precipitate size in a nickel superalloy, without complex modeling.
预测二次和三次γ'相析出物的尺寸，对于多晶镍基高温合金在苛刻应用中的开发和使用尤为重要，因为析出物的尺寸对力学性能有很大影响。许多研究致力于开发和应用复杂的数值模型，这些模型考虑了化学成分、浓度梯度和界面性质对析出物尺寸和形态的影响。在本研究中，我们选择了一种不同的方法，重点是确定二次和三次γ'相的平均尺寸与固溶处理温度冷却速率之间的相关性。数据通过高分辨率扫描电子显微镜的析出物尺寸分布分析来收集。这种相关性以幂律的形式表示，通过实验测量数据建立，并基于成熟的热力学原理，通过重新推导麦克林析出物生长理论进行合理化。具体而言，对麦克林模型进行了重新构建，以考虑冷却速率的影响。尽管该模型很简单，但导出的模型能够正确捕捉这种相关性，并且能够在不进行复杂建模的情况下预测镍基高温合金中二次和三次γ'相析出物的平均尺寸。
