Effects of lattice misfit of γ/γ′ phases on hydrogen embrittlement behavior in Ni-based single crystal superalloy

• DOI: 10.1016/j.jmrt.2024.04.206
• Publication Date: 2024-04-27T15:48:34Z
• Authors: Jisung Yoo; Hyeonseok Kwon; Seungwoo Song; Jeonghyeon Do; Dae Won Yun; Hyoung Seop Kim; Seung-gun Lee; In Soo Kim; Baig-Gyu Choi
• Keywords: Embrittlement; Deformation mechanism

The effect of γ/γ′ phase lattice misfit on hydrogen embrittlement (HE) behavior was fundamentally investigated by utilizing a Ni-based single crystal CMSX-4 superalloy with simple microstructure that can exclude the H-trapping effects grain boundary, c-vacancy, and dislocation. Increasing isothermal aging time increased γ′ precipitate size while maintaining its volume fraction fully coherent interface. magnitude negative between γ phases from −0.08 to −0.22% according coarsening, resulting in well-developed tensile-strain field within precipitate. enhanced activation energy for H-desorption 31.9 35.1 kJ/mol. Therefore, H is preferentially distributed along interface even before deformation. basically promotes slip planarity through H-enhanced localized plasticity (HELP) mechanism alloys, which dominant deformation behavior. As possesses larger misfit, becomes trapped as diffusible-state at interface, cuboidal brittle fracture {001} planes. In this process, HELP facilitated localization Thus, HE distinctly transitioned an interaction decohesion mechanisms (HEDE) increase misfit. correlating microstructural characterization, behavior, crystallographic analysis.