基于位错密度演化的6008铝合金动态冲击本构模型  

Dynamic impact constitutive model of 6008 aluminum alloy based on evolution dislocation density

作　　者：朱志武 张光瀚 冯超 肖守讷 朱涛 Zhiwu Zhu;Guanghan Zhang;Chao Feng;Shoune Xiao;Tao Zhu(Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province,School of Mechanics and Aerospace Engineering,Southwesi Jiaotong University,Chengdu 610031,China;Siate Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province,School of Mechanics and Aerospace Engineering,Southwesi Jiaotong University,Chengdu 610031,China [2]Siate Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu 610031,China

出　　处：《Acta Mechanica Sinica》2023年第7期94-108,共15页力学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11972028 and 12272328);the Development Project of Original Scientific Research Instrument of Southwest Jiaotong University(Grant No.XJ2021KJZK045);the Natural Science Foundation of Sichuan Province(Grant No.2022NSFSC0420).

摘　　要：在本研究中,使用分离式霍普金森压杆设备和透射电子显微镜对6008铝合金进行了系统的实验研究.分析了6008铝合金在不同应变率和温度下的宏微观力学响应及塑性变形机理.微观实验结果表明,在冲击压缩条件下,应变率的增加导致位错密度的增加.此外,第二相颗粒沉淀阻碍了位错运动导致流动应力增大.材料的冲击变形涉及过饱和固溶体的溶解和高温冲击载荷期间的热激活运动.基于位错微观密度的演化机制,建立了冲击动力学的本构模型.主要考虑了内应力中晶粒尺寸和位错亚胞对固定位错密度演化的影响.该模型基于热激活位错运动,其新颖之处在于包含了等效应力.本文所提出的本构模型可以合理地描述6008铝合金在宽应变率和温度范围内的动态塑性演化.In this study,a systematic experimental evaluation of 6008 Al alloys was conducted using split Hopkinson pressure bar equipment and a transmission electron microscope.The macro-and micro-mechanical responses and mechanisms for plastic deformation of 6008 Al alloy were analyzed at various strain rates and temperatures.At the microscopic level,the results revealed that an increase in the strain rate led to an increase in dislocation density under impact compression conditions.Moreover,dislocation movement and flow stress were prevented by second-phase particle precipitation.In contrast,impact deformation of the material involved the dissolution of the supersaturated solid solution and thermal activation during high temperature impact loading.A constitutive model of impact dynamics was constructed based on the evolutionary mechanism of the microscopic density of dislocation.The main consideration was the internal stress,which took into account the effects of grain size and dislocation sub-cells on the evolution of the density of immobile dislocation.The novelty of this model,which is based on thermally activated dislocation motion,lies with the inclusion of equivalent stress.The proposed constitutive model can reasonably describe the dynamic plastic evolution of 6008 Al alloys over a wide range of strain rates and temperatures.

关 键 词：位错运动 热激活 冲击动力学 流动应力 分离式霍普金森压杆 过饱和固溶体 透射电子显微镜 动态冲击 

分 类 号：TG146.21[一般工业技术—材料科学与工程]