Abstract Metastable γ″ (D022-Ni3Nb) particles are strengthening precipitates for commercial Inconel 625 Ni-based superalloy. Understanding their morphological evolution is critical for evaluating its hardening effects and guiding heat treatments to improve its yield strength. Here we present a phase-field model to model and analyze the nucleation and growth kinetics of metastable γ″ in Inconel 625 during isothermal and non-isothermal aging conditions with thermodynamic properties, diffusion coefficients, and misfit strain data from both the literature and calibration to experimental results. We implemented the classical nucleation theory to introduce local nucleation taking into account local supersaturation. The simulated mean particle length and aspect ratio are in agreement with experimental data at 600 °C and 650 °C during isothermal aging. Utilizing the phase-field simulation results as input parameters, the coherency strengthening effect of γ″ as a function of aging temperature and time is predicted. A multistage aging strategy to optimize the γ″ strengthening effect and to reduce aging times using the developed phase-field model and coherency strengthening model is suggested.

中文翻译：

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Inconel 625热处理过程中γ″析出动力学的三维相场模拟

摘要 亚稳态 γ″ (D022-Ni3Nb) 颗粒是商业 Inconel 625 Ni 基高温合金的强化析出物。了解它们的形态演变对于评估其硬化效果和指导热处理以提高其屈服强度至关重要。在这里，我们提出了一个相场模型来模拟和分析 Inconel 625 中亚稳态 γ″ 在等温和非等温老化条件下的成核和生长动力学，具有热力学性质、扩散系数和来自文献和校准的错配应变数据实验结果。我们实施了经典成核理论以引入考虑局部过饱和的局部成核。模拟的平均颗粒长度和纵横比与等温老化期间 600 °C 和 650 °C 的实验数据一致。利用相场模拟结果作为输入参数，预测γ″随时效温度和时间变化的相干性强化效果。提出了一种多阶段时效策略，以优化 γ″ 强化效果并使用开发的相场模型和相干强化模型减少时效时间。