BCC Fe中P晶界偏析对拉伸变形行为影响的分子动力学研究  

Molecular Dynamics Study on Influence of P Segregation at BCC Fe Grain Boundary on Tensile Deformation Behavior

作　　者：陈梦瑶 贺新福[1] 毛文略 赵永鹏 汪淑敏 赵宏睿 CHEN Mengyao;HE Xinfu;MAO Wenlue;ZHAO Yongpeng;WANG Shumin;ZHAO Hongrui(Department of Reactor Engineering Technology,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院反应堆工程技术研究所,北京102413

出　　处：《原子能科学技术》2024年第S01期110-120,共11页Atomic Energy Science and Technology

基　　金：稳定支持科研项目(BJ020261223286);国家自然科学基金(51201184);中核集团“青年英才”项目。

摘　　要：晶界是金属材料中重要的微观结构,并且晶界上的位错形核对材料变形起着至关重要的作用。本文通过分子动力学模拟研究了BCC Fe中对称倾侧晶界的位错形核机制和孪晶机制,分析了P的晶界偏析对位错变形行为的影响机理。对于(111)晶界体系,位错形核扩展主导拉伸变形行为。而对于(112)孪晶界体系,拉伸变形主要是由孪晶主导,体系发生BCC-FCC相变。针对5个对称倾侧晶界(旋转角为30°~160°)体系,在不同温度下(300 K和600 K)施加拉伸载荷,结果表明位错形核受晶界类型和温度影响。与300 K相比,600 K下体系强度降低,促进位错形核。同时,从原子微观结构、体系能量两个角度,研究P的晶界偏析对位错形核的影响机理。本文提供了晶界位错形核的原子机制,有助于理解P在BCC Fe中的偏析对晶界变形行为和力学性能的影响。Grain boundaries are important microstructures in metallic materials,and dislocation nucleation on grain boundaries plays a crucial role in material deformation.Studies on P segregation on grain boundaries typically focus on segregation behavior at substitution or interstitial positions.Less attention is given to the interaction of a certain amount of P with dislocation nucleation and grain boundary structural units during deformation.Previous deformation mechanism studies often qualitatively determine mechanisms,struggling to quantitatively explain their roles.This paper offers an atomic mechanism for grain boundary dislocation nucleation,aiding in understanding of the effect of P segregation in BCC Fe on mechanical properties.In this paper,a large-scale atomic/molecular massively parallel simulation(LAMMPS)program was employed.It investigated the effect of P segregation in BCC Fe grain boundary on the tensile deformation behavior.Binary Fe-P embedded atom potential was used for the calculation of stress-strain curves and dislocation activation energy densities.The analysis of P segregation behavior on different grain boundary structures and the effect of temperature was conducted using visual analysis software(OVITO.3.10).To illustrate the elastic-plastic component of the strain during loading,a set of kinematic parameters based on continuum medium mechanics was employed.The atomic deformation tensor of the deformation gradient was calculated using the nearest-neighbor table approximation of the continuum medium field around each atom.Additionally,the mechanisms of dislocation nucleation and twinning were discussed for the symmetrically inclined grain boundaries in BCC Fe.For the(111)grain boundary system,dislocation nucleation extends and dominates the deformation behavior.For the(112)twin grain boundary system,tensile deformation is mainly controlled by twin grain boundary,resulting in BCC-FCC phase transitions.Tensile loads were applied to different grain boundaries at temperatures of 300 K and 600 K.The res

关 键 词：磷偏析 BCC Fe 拉伸变形行为 

分 类 号：TL341[核科学技术—核技术及应用]