The morphological evolution and coarsening kinetics of γ′ precipitates in a Re-containing Ni-based single crystal superalloy were investigated during isothermal aging at 900, 950 and 1000 °C. After heat treatment, well-defined cuboidal γ′ precipitates with low misfit was obtained within the experimental alloy. Then coarsening rate constants and particle size distribution (PSD) of γ′ phases were calculated and specified based on the measured precipitate sizes for varying periods of aging times from 100 to 2000 h. After aging for 2000 h, γ′ precipitates maintained cubical shape at 900 °C, while exhibited sphere at 950 and 1000 °C. Coarsening models based on diffusion-controlled process with a functional relationship of r³ vs. t (classic Lifshitz-Slyozov-Wagner coarsening model) and interface-controlled model with a function of r² vs. t (trans-interface diffusion-controlled coarsening model) were investigated to fit between the experimental results and theoretical analysis. It was found that Re as the slowest diffusing solute in the alloy constituted the rate-limited step for coarsening based on LSW model, while the process limiting coarsening as governed by an interface diffusion process could possibly be related to the Al diffusion through the γ/γ′ interface. The PSDs and coarsening exponent were discussed by comparing the experimental data with predictions of LSW and TIDC models. Finally, coarsening mechanism could be divided into four regimes: (i) coarsening by diffusion-controlled; (ii) coarsening by diffusion and interface co-controlled; (iii) coarsening by interface-controlled; (iv) coarsening by interface-controlled accompanied with γ′ coalescence.

研究了在900、950和1000°C等温时效过程中，含Re的Ni基单晶高温合金中γ'析出物的形貌演化和粗化动力学。热处理后，在实验合金中获得了轮廓分明的长方体γ'沉淀，失配率低。然后根据在100至2000 h的不同老化时间段内测得的沉淀物尺寸，计算并确定γ'相的粗化速率常数和粒径分布（PSD）。老化2000 h后，γ'沉淀在900°C时保持立方体形状，而在950和1000°C时呈现球形。基于r为函数关系的扩散控制过程的粗化模型^研究了3 vs. t（经典的Lifshitz-Slyozov-Wagner粗化模型）和具有r ² vs. t的函数的界面控制模型（跨界面扩散控制的粗糙化模型），以拟合实验结果和理论分析。研究发现，作为合金中最慢的扩散溶质的Re构成了基于LSW模型的粗化的限速步骤，而受界面扩散过程控制的粗化过程可能与Al通过γ /扩散有关。γ′接口。通过将实验数据与LSW和TIDC模型的预测进行比较，讨论了PSD和粗化指数。最后，粗化机制可以分为四个机制：（i）通过扩散控制进行粗化；（ii）通过扩散和界面共同控制来粗化；（iii）通过界面控制进行粗化；（iv）通过界面控制伴随γ'合并进行粗化。