B对Mo等元素在奥氏体钢/Cr_(2)O_(3)界面占位倾向影响的理论研究  

Theoretical study on segregation behavior of Mo and metals at the fcc-Fe/Cr_(2)O_(3) interface without or with B

作　　者：闫新[1] 董楠 张翊[1] 韩培德[1] YAN Xin;DONG Nan;ZHANG Yi;HAN Pei-De(College of Material Science and Engineering,Taiyan University of Techno logy,Taiyuan 030024,China)

机构地区：[1]太原理工大学材料科学与工程学院,太原030024

出　　处：《原子与分子物理学报》2022年第4期165-172,共8页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(518171159)。

摘　　要：超级奥氏体不锈钢中因含有更高铬、钼含量,具有极高的耐点蚀、晶间腐蚀性能,这与Mo等合金元素对钝化膜结构的影响密切相关,尤其含硼超奥钢钝化层表面Cr、Mo含量明显增加,但其原子层次的微观作用机制尚不清楚.本文采用第一性原理方法,研究了置换原子(Mo、Mn、Ni、Si),及间隙原子B在fcc-Fe/Cr_(2)O_(3)界面占位倾向,并分析了可稳定存在于界面B对这些元素偏析倾向的影响.结果表明:Mo、Mn、Ni、Si、B均可与fcc-Fe/Cr_(2)O_(3)界面结构体系形成稳定结构;Mo、Ni倾向分布于界面基体侧,Mo有向氧化层扩散的趋势,B处于fcc-Fe/Cr_(2)O_(3)界面基体侧更稳定,Mn、Si易分布于氧化层中;存在于界面B对四种元素在fcc-Fe/Cr_(2)O_(3)界面体系中的占位影响不同,有利于Mn、Mo偏析于界面基体侧,但抑制Mo向界面基体侧的偏析程度,使得Si、Ni更均匀的分布于基体. Mo等合金元素分布于界面时的态密度来看,界面处Mo与氧原子间形成较强的相互作用,Mo等原子可向O转移更多的电子,形成的MoO键表现出更强的互作用,提高了界面处原子间的结合力和稳定性;Mo+B、Mn+B、Ni+B、Si+B与fcc-Fe/Cr_(2)O_(3)界面复合体系,费米能级处的能量分别为42.34 states/eV、44.65 states/eV、43.99 states/eV、42.30 states/eV,Mo、Mn、Ni、Si对费米能级处的贡献大于B的贡献,分别由Mo的4d轨道电子、Mn的3d轨道电子、Ni的3d轨道电子和Si的3p轨道电子作出的贡献.Super austenitic stainless steel has extremely high resistance to pitting and intergranular corrosion. This is because the high content of chromium and molybdenum has an important impact on the structure of the passivation film, but the mechanism of chromium and molybdenum on the passivation layer is not yet clear. Therefore, this paper adopts the first-principles method to conduct theoretical explorations of the material system, study the segregation tendency of replacement atoms(Mo, Mn, Ni, Si) and interstitial atoms B at the fcc-Fe/Cr_(2)O_(3) interface, and analyze the influence of B on the propensity of these elements. The calculation results show that Mo, Mn, Ni, Si, B can exist stably in the fcc-Fe/Cr_(2)O_(3) interface system, Mo and Ni tend to be on the side of the interface matrix, Mo has a tendency to diffuse into the oxide layer, Mn and Si are more inclined to be distributed in the oxide layer of the interface system, and B can stably exist on the side of the fcc-Fe/Cr_(2)O_(3) interface matrix;the addition of B has different effects on the occupancy tendency of the four elements in the fcc-Fe/Cr_(2)O_(3) interface system. B on the side of the interface matrix can inhibit the segregation of Mo to the side of the interface matrix, and promote the segregation of Mn to the side of the interface matrix, so that the distribution of Ni in the interface system tends to be uniform;the density of states when Mo is distributed on the interface shows that Mo has a strong interaction with O atoms in the interface, which improves the bonding force and stability between atoms at the interface;after Mo+B, Mn+B, Ni+B and Si+B are compositely dissolved into the fcc-Fe/Cr_(2)O_(3) interface system, the energies at the Fermi level are 42.34 states/eV, 44.65 states/eV, 43.99 states/eV and 42.30 states/eV, respectively. The 4 d orbital electrons of Mo, the 3 d orbital electrons of Mn and Ni and the 3 p orbital electrons of Si provide the main contribution.

关 键 词：Fe/Cr O 第一性原理 界面 偏析 

分 类 号：O469[理学—凝聚态物理]