期刊
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
卷 231, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijmecsci.2022.107580
关键词
Shock wave; Dislocation dynamic; Hugoniot elastic limit; Nanocomposites
资金
- National Natural Science Foundation of China [11964003]
- Guangxi Natural Science Foundation [2019GXNSFAA185058, 2018GXNSFAA281291]
- LiYing Program of the Institute of Mechanics, Chinese Academy of Sciences [E1Z1011001]
In this study, molecular dynamics simulations were used to investigate the dislocation motion and interaction under shock loading of SiC/Al nanocomposites. The results showed that the Al/SiC interfaces can act as a dislocation emitter, controlling the density and direction of dislocation multiplication to achieve ultrahigh strength. The effect of nanoparticles on dislocation structure changes when the impact velocity exceeds a certain limit. Furthermore, the study revealed the abnormal shock softening effect determined by atomic velocity.
Shock tolerance is desirable for ceramic particles-reinforced metal matrix composites in many applications, where the dislocation dynamics evolution under the extreme load is the key but still elusive. Herein, we have investigated the dislocation motion and interaction under shock loading of SiC/Al nanocomposites using molecular dynamics simulations. We have demonstrated that the plastic deformation occurs at an impact velocity (0.5 km/s) lower than the Hugoniot elastic limit of aluminum due to the reflected shear wave effect. The Al/SiC interfaces act as a dislocation emitter to control dislocation multiplication density and slip direction, opening a new pathway to achieve ultrahigh-strength via shock loading. When the impact velocity (1.0 or 1.5 km/s) exceeds the Hugoniot elastic limit, the effect of nanoparticles on dislocation structure has changed from multiplying to retarding dislocations. The spall strength of composites improves due to dislocations pile-up at interface. Instead, the damage in the matrix is exacerbated, owing to the enhanced residual peak stress and interface reflection waves. In addition, the effect of abnormal shock softening determined by atomic velocity is revealed, which could be suppressed by increasing impact energy dissipation. Meanwhile, dynamic compressive strength depends on pressure and dislocation structures evolution. Our atomistic insights might be helpful in designing advanced shock-tolerant materials.
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