硼在fcc-Fe晶界偏析及对界面结合能力影响的第一性原理研究  

First-principles study of boron segregation in fcc-Fe grain boundaries and its influence on interface adhesive strength

作　　者：徐攀攀 韩培德[1] 张竹霞[2] 张彩丽[1] 董楠 王剑[1] Xu Pan-Pan;Han Pei-De;Zhang Zhu-Xia;Zhang Cai-Li;Dong Nan;Wang Jian(College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,China;College of Aeronautics and Astronautics,Taiyuan University of Technology,Jinzhong 030600,China)

机构地区：[1]太原理工大学材料科学与工程学院,太原030024 [2]太原理工大学航空航天学院,晋中030600

出　　处：《物理学报》2021年第16期235-243,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51871159,U1860204);山西省自然科学基金(批准号:201801D221125)资助的课题。

摘　　要：基于第一性原理的密度泛函理论计算了B在fcc-Fe的∑3(112),∑5(210),∑5(310),∑9(114),∑9(221)和∑11(113)六种对称倾斜晶界的偏析行为,从原子和电子层次揭示了B的偏析机制.结果表明:B更易偏析于∑5(210),∑5(310)和∑9(114)晶界,而在∑9(221),∑3(112)和∑11(113)晶界偏析的倾向较弱;B优先占据配位数最大、五面体或六面体构型的位置;拉伸实验和Rice-Wang热力学模型计算表明,B在晶界的偏析可提高界面的结合能力;B在E9(114)晶界偏析后电子结构引起局部电荷密度增加导致的化学效应优于结构变化带来的不利影响,B-p电子与Fe-s电子间的强相互作用提高了界面的结合能力.本研究结果对B优化奥氏体不锈钢界面结构具有一定指导作用.Boron,a commonly used microalloying element in steel,is distributed mainly at the grain boundary of stainless steel and plays an important role in regulating the mechanical,corrosion resistance and grain boundary structure of stainless steel.Owing to the small amount of boron added into the steel,it is difficult experimentally to detect the traces of boron segregation at the grain boundary,not to mention analyzing the structural characteristics of the boron segregation grain boundary.First-principles density functional theory(DFT)provides convenience in analyzing the existence mode and mechanism of boron in austenitic steel from the atomic level.Combining with the actual grain boundary structure types in austenitic stainless steel,Fcc-Fe∑3(112),∑5(210),∑5(310),∑9(114),∑9(221)and∑11(113)symmetric tilt grain boundaries are constructed based on DFT,and the segregation behaviors of boron atoms at the six grain boundaries are studied to reveal the segregation mechanism from the atomic and electronic level.The results show that boron segregation occurs mostly at∑5(210),∑5(310)and∑9(114)grain boundaries,while a relatively weak segregation tendency is observed at∑9(221),∑3(112)and∑11(113)grain boundaries;boron atom preferentially occupies the pentahedral or hexahedral segregation position with the largest coordination number;the interface adhesive strength at grain boundaries is improved by the segregation of boron according to the tensile test,which complies with the calculation results of Rice-Wang thermodynamic model;the chemical effect caused by the increase of local charge density after boron segregation at∑9(114)grain boundary outstrips the adverse effect of structural changes,and the strong interaction between B-p electrons and Fe-s electrons improves the interface adhesive strength.The results provide a reference for using boron to optimize the interface structure of austenitic stainless-steel.

关 键 词：奥氏体钢 硼 第一性原理 偏析 界面结合能力 

分 类 号：TG142.71[一般工业技术—材料科学与工程]