朱熠奇,殷艳,周留成,易敏.激光冲击铝合金微结构演化及力学行为的分子动力学模拟[J].表面技术,2022,51(11):1-9, 57.
ZHU Yi-qi,YIN Yan,ZHOU Liu-cheng,YI Min.Microstructure Evolution and Mechanical Behavior of Laser-shocked Aluminium Alloy by Molecular Dynamics Simulations[J].Surface Technology,2022,51(11):1-9, 57 |
| 激光冲击铝合金微结构演化及力学行为的分子动力学模拟 |
| Microstructure Evolution and Mechanical Behavior of Laser-shocked Aluminium Alloy by Molecular Dynamics Simulations |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.11.001 |
| 中文关键词: 铝合金 激光冲击 微结构 残余应力 位错密度 力学行为 分子动力学 |
| 英文关键词:aluminium alloy laser shock microstructure residual stress dislocation density mechanical behavior molecular dynamics |
| 基金项目:国家科技重大专项(J2019-IV-0014-0082);国家海外高层次人才引进计划青年项目;中央高校基本科研业务费;江苏高校优势学科建设工程资助项目 |
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| Author | Institution |
| ZHU Yi-qi | State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing, 210016, China ;College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China |
| YIN Yan | State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing, 210016, China ;College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China |
| ZHOU Liu-cheng | Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi'an 710038, China |
| YI Min | State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing, 210016, China ;College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China |
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| 中文摘要: |
| 目的 揭示激光冲击铝合金的微结构演化过程及塑性变形机制，探究残余应力产生的机理，为激光冲击提升铝合金力学性能提供理论参考。方法 基于分子动力学模拟，采用活塞冲击法实现多晶铝合金(Al-Mg-Zn-Cu)在不同加载速度下的冲击强化。利用共邻分析法和位错提取法，研究铝合金的微结构演化过程、位错分布以及激光冲击影响铝合金力学性能的内在机理。结果 在冲击波加载阶段，当高速冲击波作用时，铝合金出现大量滑移系，产生高密度位错。在保载阶段，位错集中在晶界附近，导致多晶铝合金发生晶界塑性变形。在卸载阶段，不同类型位错之间进行了相互转化。铝合金两端晶粒和晶界的塑性变形，导致了残余压应力的产生。对完全卸载后的铝合金进行单轴拉伸模拟，发现0.7 km/s和1.0 km/s的冲击速度下，残余压应力抵消了部分拉伸应力，变形晶界附近产生新的位错，且晶界发生迁移和合并，导致极限应力分别提升15%和22%。结论 激光冲击对Al-Mg-Zn-Cu铝合金的微结构及力学性能影响显著，在高速冲击波作用下，铝合金两端发生剧烈的塑性变形，导致残余压应力的产生。单轴拉伸时，残余压应力抵消了部分拉伸应力，且铝合金晶粒内发生原子变形产生新的位错，同时晶界发生运动，最终使得极限应力增大，铝合金的力学性能得到提升。 |
| 英文摘要: |
| This work aims to reveal the process of microstructure evolution as well as the atomic-scale mechanism of plastic deformation and residual stress in laser-shocked aluminium alloy, which could provide the theoretical guidance for improving the mechanical property of aluminium alloy by the laser shock. Here, a piston method based on molecular dynamics was used to simulate the laser-shocked polycrystalline aluminium alloy (Al-Mg-Zn-Cu) with different shock velocities. The response of aluminium alloy during the shocking-holding-unloading process was expounded in detail. The microstructure evolution and dislocation distribution, as well as the influence of laser shock on the mechanical properties of aluminium alloy, were analyzed by common neighbor analysis and dislocation extraction algorithm method. The piston velocity was found to greatly influence the laser-shocked aluminium alloy, especially the high piston velocity. With a piston velocity (Up) of 1.0 km/s, sliding motion of the systems become active and the corresponding dislocation density increased. Partial dislocation and stacking faults were converted to perfect dislocation during the holding process, and dislocations mainly distributed around the grain boundary. Meanwhile, the total dislocation density of the system kept stable during the shocking-holding-unloading process, with the Shockley dislocation transformed into other dislocations. High dislocation density was distributed at both ends of the laser-shocked aluminium alloy, leading to the plasticity deformation in the grain and grain boundary. Due to this plastic deformation, the residual compressive stress appeared at the surface of laser-shocked aluminium alloy, and the maximum residual stress was up to 1.2 GPa. A uniaxial tensile simulation of laser-shocked aluminium alloy further showed that the ultimate stress of aluminium alloy was almost not affected by the laser shock with Up=0.3 km/s. However, the ultimate stress was increased by 15% and 22% in laser-shocked aluminium alloy with Up=0.7 km/s and 1.0 km/s, respectively. The residual compress stress of laser-shocked aluminium alloy cancels out part of the external tensile stress at both ends of model, resulting in an increase of the global tensile stress. Meanwhile, the increasing dislocation density and the migration of grain boundary indicated the plastic deformation at the yield stage of laser-shocked aluminium alloy, which led to the improvement of the ultimate stress. In summary, the microstructure and mechanical property of polycrystalline aluminium alloy (Al-Mg-Zn-Cu) is notably influenced by laser shock with moderately high impact velocities. Aluminium alloy has a high dislocation density at both ends of the model after high shock velocity. High dislocation movement induces the plastic deformation of grain and grain boundary, resulting in the residual compressive stress at the surface of aluminium alloy. When a uniaxial tension is applied, the plastic deformation of laser-shocked aluminium alloy at the yield stage is mediated by increasing dislocation and grain boundary movement of the deformed grain boundary, finally resulting in the improvement of mechanical property. |
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