Wan Changfeng, Wang Biao
School of Material Science and Engineering, Dongguan University of Technology, Dongguan 523808, China.
Materials (Basel). 2025 May 23;18(11):2436. doi: 10.3390/ma18112436.
In this work, a crystal plasticity (CP)-based continuum modeling approach is employed to investigate the interaction between dislocations and coherent γ″ precipitates in the Inconel 718 (IN718) superalloy. A finite element (FE) model is developed to accurately represent realistic microstructures in IN718, specifically incorporating a disk-shaped precipitate embedded within a matrix phase. A length-scale-dependent CP modeling simulation informed by molecular dynamics (MD) findings is conducted. The results indicate that the three γ″ variants behave differently under uniaxial loading conditions, altering the deformation process in the γ phase and leading to significant strain and stress heterogeneities. The presence of dislocation shearing in the γ″ variants reduces the localization of strain and dislocation densities in the adjacent γ phase. The strain gradient-governed geometrically necessary dislocation (GND) density plays a dominant role in influencing strain hardening behavior. The length scale effect is further quantified by considering four different precipitate sizes, with the major axis ranging from 12.5 nm to 100 nm. The findings show that smaller precipitate sizes result in stronger strain hardening, and the size of γ″ precipitates significantly alters GND density evolution.
在这项工作中，采用了一种基于晶体塑性（CP）的连续介质建模方法来研究Inconel 718（IN718）高温合金中位错与相干γ″析出相之间的相互作用。开发了一个有限元（FE）模型来精确表征IN718中的实际微观结构，具体包括在基体相中嵌入一个盘状析出相。进行了基于分子动力学（MD）结果的长度尺度相关的CP建模模拟。结果表明，在单轴加载条件下，三种γ″变体的行为不同，改变了γ相中的变形过程，并导致显著的应变和应力不均匀性。γ″变体中位错剪切的存在降低了相邻γ相中的应变局部化和位错密度。应变梯度控制的几何必要位错（GND）密度在影响应变硬化行为方面起主导作用。通过考虑四种不同的析出相尺寸（长轴范围从12.5 nm到100 nm）进一步量化了长度尺度效应。研究结果表明，较小的析出相尺寸导致更强的应变硬化，并且γ″析出相的尺寸显著改变了GND密度的演变。
