Hydrogen Trapping and Embrittlement Behavior in a Second-Generation Ni-Based Single Crystal Superalloy

The present study explores the hydrogen trapping capability and hydrogen embrittlement (HE) behaviors of a second-generation single crystal (SX) superalloy. The susceptibility of HE improves with the increased hydrogen charging duration. Hydrogen induces more cleavages, micro-cracks and denser slip traces. Hydrogen facilitates the formation of nano-voids and the activation of high-density dislocations, leading to denser slip bands which are initiation sites of micro-cracks. Hydrogen is prone to be solutioned in the γ matrix and reversibly trapped at the γ/γ' interface. The First-principles calculations indicate that hydrogen reduces the binding strength at the γ/γ' interface, which promotes the propagation of micro-cracks.