镍基高温合金中的位错动力学：基于原子尺度模拟参数化位错轨迹
Dislocation dynamics in Ni-based superalloys: Parameterising dislocation trajectories from atomistic simulations
AI总结：
本研究利用纯镍分子动力学轨迹，通过 DE-MC 方法标定带不确定性的位错运动方程参数，为镍基高温合金变形代理模型奠定基础。
摘要：
镍基高温合金微观结构中的纳米尺度析出相会阻碍位错运动，从而在高温下产生显著的强化效应。我们采用基于经典有效势的分子动力学（MD）方法，观察了代表镍固溶体基体的纯镍中一条 a/2⟨110⟩{111} 刃位错在剪切作用下的运动，并提取了位错位置。我们展示了差分进化蒙特卡洛（DE-MC）分析如何能够有效地为位错线运动方程寻找参数，并给出量化的不确定性。所关注的参数包括有效质量、拖曳系数以及位错所受的力。边缘参数分布和联合后验分布由 DE-MC 算法产生的已接受样本估计得到。运动方程和参数分布被用于预测模拟时间步上的位错位置和速度，所得平均拟合与 MD 轨迹相符，均方根误差（RMSE）为 0.2 nm。我们还讨论了所选模型如何扩展，以考虑多个位错的存在以及位错—析出相相互作用。本工作是构建描述镍基高温合金变形行为的预测性代理模型的第一步。
英文摘要：
Nanoscale precipitates in the microstructure of nickel-based superalloys hinder dislocation motion, which results in an extraordinary strengthening effect at elevated temperatures. We used molecular dynamics (MD) with classical effective potential to observe the movement of an $\frac{a}{2}\langle110\rangle\{111\}$ edge dislocation under shear in pure Ni, which represents the Ni solid solution matrix, and extracted the locations of the dislocations. We show how a Differential Evolution Monte Carlo (DE-MC) analysis is an effective way to find the parameters of an equation of motion for the dislocation lines with quantified uncertainties. The parameters of interest were the effective mass, drag coefficient, and force experienced by the dislocation. The marginal parameter and joint posterior distributions were estimated from the accepted samples produced by the DE-MC algorithm. The equation of motion and parameter distributions were used to predict the dislocation positions and velocities at the simulation timesteps, and the mean fit was found to match the MD trajectories with a root mean square error (RMSE) of \SI{0.2}{\nano\metre}. We also discuss how the selected model can be extended to account for the presence of multiple dislocations as well as dislocation-precipitate interactions. This work serves as the first step towards building a predictive surrogate model that describes the deformation behaviour of Ni-based superalloys.
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