原子模拟铼对镍基单晶高温合金低周疲劳的影响  

ATOMIC SIMULATION OF THE EFFECT OF RHENIUM ON LOW CYCLE FATIGUE OF Ni-BASED SINGLE CRYSTAL SUPERALLOYS

作　　者：丁子峻 申宏飞 吴文平 Ding Zijun;Shen Hongfei;Wu Wenping(Department of Engineering Mechanics,School of Civil Engineering and Architecture,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学土木建筑工程学院工程力学系,武汉430072

出　　处：《力学学报》2023年第9期1960-1970,共11页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金资助项目(12172259和11772236)。

摘　　要：镍基单晶高温合金是制造航空发动机和重型燃气轮机涡轮叶片的关键材料,叶片在服役过程中遭受严重的低周疲劳(LCF).以往的实验研究表明铼(Re)的添加有效提高了高温合金的疲劳力学性能,但对其原因尚没有明确的解释.文章采用分子动力学模拟研究了Re对镍基单晶高温合金低周疲劳力学性能和微观结构演化的影响,从原子尺度解释了Re对提高镍基单晶高温合金低周疲劳力学性能和寿命的主要原因.结果表明Re的加入有效提高了镍基单晶高温合金的循环应力幅值和抗塑性变形能力,降低了高温合金的塑性应变和塑性应变能密度.在微观结构方面,Re的添加可以降低高温合金的位错密度,导致γ'沉淀相发生更少的塑性变形,降低了高温合金的塑性应变能密度.这主要是因为高温合金循环变形过程中Re原子对位错运动产生的钉扎与拖拽效应,导致位错运动受到更强的阻碍,从而导致含Re高温合金具有更高的循环应力幅值和更少的塑性变形.此外,由于Re对位错运动的钉扎与拖拽效应,提高了含Re高温合金微观结构的稳定性,从而产生更强的抗疲劳性能,提高了合金的疲劳寿命.研究成果有助于从原子尺度进一步理解镍基单晶高温合金中的低周疲劳性能及其Re效应,并为新一代镍基单晶高温合金的开发设计提供理论支撑.Ni-based single crystal superalloys are key materials used in the manufacturing of turbine blades for aerospace engines and heavy-duty gas turbines.The turbine blade suffers severe low cycle fatigue(LCF)loading during operation.Previous experimental studies have demonstrated that the addition of rhenium(Re)effectively enhances the fatigue mechanical properties of superalloys.However,the underlying reasons for this improvement have not been clearly explained.In this work,the effects of Re on the mechanical properties and microstructure evolution of Ni-based single crystal superalloys under LCF loading are investigated by molecular dynamics simulations,the main reasons why Re improves the LCF mechanical properties and fatigue life of Ni-based single crystal superalloys are explained from the atomic scale.The results show that the addition of Re to the Ni-based single crystal superalloys can effectively increase the cyclic stress amplitude and improve the plastic deformation resistance.Additionally,it can reduce the plastic strain and plastic strain energy density of the superalloys.In terms of microstructure,the addition of Re can reduce the dislocation density of the superalloys,resulting in less plastic deformation in theγ'precipitate phase,and thus reduce the plastic strain energy density of the superalloys.This is mainly due to the pinning and dragging effects of Re atoms on the dislocation motion,which lead to a stronger hindrance of the dislocation motion,resulting in higher cyclic stress amplitude and less plastic deformation of the superalloys with Re addition.In addition,due to the pinning and dragging effects of Re on the dislocation motion,the microstructure stability of the superalloys with Re addition is improved,resulting in stronger fatigue resistance and longer fatigue life.The research is helpful to further understand the LCF mechanical properties and Re effect at the atomic scale.Moreover,it can also provide theoretical support for the development and design of new generation Ni-based single crys

关 键 词：镍基单晶高温合金 低周疲劳 微观结构 铼效应 分子动力学模拟 

分 类 号：O34[理学—固体力学]