剪切应力下温度对纳米晶Al-Mg-Si合金近表面微观结构演变的影响  

Effect of temperature on near-surface microstructural evolution in nanocrystalline metal under shear stress

作　　者：雷刚 邢健瑞 高海涛 崔晓辉 喻海良 LEI Gang;XING Jian-rui;GAO Hai-tao;CUI Xiao-hui;YU Hai-liang(College of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China;State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,Changsha 410083,China;Light Alloy Research Institute,Central South University,Changsha 410083,China)

机构地区：[1]College of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China [2]State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,Changsha 410083,China [3]Light Alloy Research Institute,Central South University,Changsha 410083,China

出　　处：《Journal of Central South University》2023年第10期3173-3186,共14页中南大学学报（英文版）

基　　金：Project(2022GK4032)supported by High-tech Industry Technology Innovation Leading Plan of Hunan Province,China;Project(2019CX006)supported by the Innovation Driven Program of Central South University,China。

摘　　要：采用分子动力学模拟方法研究了不同压力和速度下纳米晶Al-Mg-Si的微观结构演变中的温度效应。通过微观结构的定量表征提出了变形机制图,给出了不同温度和载荷下弹性-塑性转变、堆垛层错、晶粒细化和剪切层形成的“相图”。温度的变化会改变堆垛层错(SFs)的运动和微观结构的完整性。在300 K时,SFs以单条迹线的形式出现,而在77 K时则以多条平行线的形式出现。与300 K相比,77 K下样品晶粒旋转和滑移运动受限,微观结构难以重排。在77 K时,在外部载荷作用下晶粒细化程度更高(最高可细化13.2%,而300 K下最高仅为8.3%),从而产生更多晶界面,而且特殊晶界(以Σ3为代表)变化幅度明显,且总体含量较高。在105倍大气压的载荷下,样品的结构完整性突然下降。在最快速度下的变形恢复到与最慢速度几乎相同的低水平。Molecular dynamics simulations were used to investigate the temperature effect in the microstructural evolution of nanocrystalline Al-Mg-Si alloy under different pressures and velocities.A deformation mechanism map is proposed through quantitative characterization of the microstructural evolution.This map provides a“phase diagram”illustrating the elastic-plastic transition,stacking faults(SFs),grain refinement,and shear layer formation under different temperatures and loads.Changes in temperature alter SFs motion and microstructural integrity.SFs appear in the form of single trace line(300 K)and multiple parallel lines(77 K),respectively.Compared to 300 K,the rotation and slip motion of grains in the sample are restricted at 77 K,making it difficult for the microstructure to rearrange.Under external loading,the degree of grain refinement is greater at 77 K(up to 13.2%refinement)compared to the refinement at 300 K(maximum~8.3%).This leads to the generation of a greater number of grain boundaries(GBs)and SFs.Additionally,there is a significant variation in the special GBs(represented byΣ3)with a relatively high overall content.A sudden drop in integrity occurs at a pressure of 105 atm.And the deformation at the highest velocity recovers to almost the same low level as at the lowest velocity.

关 键 词：纳米晶铝合金 微观结构演变 干滑动 温度效应 分子动力学 

分 类 号：TG1[金属学及工艺—金属学]