Heterogeneous segregation behavior of Nb at the stepped migrating interface during phase transformation

作者：Dong, Haokai^*; Zhang, Yongjie^*; Miyamoto, Goro; Inomoto, Masahiro; Zhang, Weiwen; Liu, Lehua; Chen, Hao; Furuhara, Tadashi

来源：Scripta Materialia, 2023, 222: 115038.

DOI：10.1016/j.scriptamat.2022.115038

• Steel
• Alloying element
• Interface segregation
• Ledge structure
• Solute drag effect

Not as generally-assumed 'smooth', the actual interface should consist of ledge structure with riser and terrace due to crystallographic constraint. However, the combined information of structure and chemistry for such stepped interface has not yet been sufficiently explored. Herein the segregation behaviors of Nb at the migrating ferrite/austenite interface with ledge structure but totally different character are investigated. For the incoherent interface, a typical heterogeneous feature that the Nb atoms segregate at the less mobile terrace rather than at the mobile riser is captured for the first time, while those segregation are absent at the semicoherent interface. By fitting the Nb trans-interface diffusivity, the theoretical calculation based on solute drag theory can well explain the experimental measurements for both types of interfaces. The present results may shed new light on the nanoscaled segregation behaviors of alloying element and stimulate more reliable simulations on the diffusional transformation with ledgewise growth mode.

• 单位
  清华大学; 1