Wan Chang-Feng, Sun Li-Gang, Qin Hai-Long, Bi Zhong-Nan, Li Dong-Feng
School of Science, Harbin Institute of Technology, Shenzhen 518055, China.
Beijing Key Laboratory of Advanced High Temperature Materials, Central Iron and Steel Research Institute, Beijing 100081, China.
Materials (Basel). 2023 Sep 9;16(18):6140. doi: 10.3390/ma16186140.
In the present paper, the dislocation-precipitate interaction in the Inconel 718 superalloy is studied by means of molecular dynamics simulation. The atomistic model composed of the ellipsoidal Ni3Nb precipitate (γ″ phase) and the Ni matrix is constructed, and tensile tests on the composite Ni3Nb@Ni system along different loading directions are simulated. The dislocation propagation behaviors in the precipitate interior and at the surface of the precipitate are characterized. The results indicate that the dislocation shearing and bypassing simultaneously occur during plastic deformation. The contact position of the dislocation on the surface of the precipitate could affect the penetration depth of the dislocation. The maximum obstacle size, allowing for the dislocation shearing on the slip planes, is found to be close to 20 nm. The investigation of anisotropic plastic deformation behavior shows that the composite system under the loading direction along the major axis of the precipitate experiences stronger shear strain localizations than that with the loading direction along the minor axis of the precipitate. The precipitate size effect is quantified, indicating that the larger the precipitate, the lower the elastic limit of the flow stress of the composite system. The dislocation accumulations in the precipitate are also examined with the dislocation densities given on specific slip systems. These findings provide atomistic insights into the mechanical behavior of nickel-based superalloys with nano-precipitates.
在本文中，通过分子动力学模拟研究了Inconel 718高温合金中的位错 - 析出物相互作用。构建了由椭球形Ni3Nb析出物（γ″相）和Ni基体组成的原子模型，并模拟了复合Ni3Nb@Ni体系沿不同加载方向的拉伸试验。表征了析出物内部和析出物表面的位错传播行为。结果表明，在塑性变形过程中位错同时发生剪切和绕过。位错在析出物表面的接触位置会影响位错的穿透深度。发现允许位错在滑移面上剪切的最大障碍物尺寸接近20 nm。各向异性塑性变形行为的研究表明，沿析出物长轴方向加载的复合体系比沿析出物短轴方向加载的体系经历更强的剪切应变局部化。对析出物尺寸效应进行了量化，表明析出物越大，复合体系流动应力的弹性极限越低。还通过特定滑移系上的位错密度研究了析出物中的位错积累。这些发现为具有纳米析出物的镍基高温合金的力学行为提供了原子层面的见解。
