Interactions of Re and hydrogen at γ/γ′ interfaces enhanced hydrogen-embrittlement resistance of Re-optimized Ni-based superalloy

This work elucidates the interactions between Re and hydrogen at γ/γ′ interfaces, enhancing the hydrogen-embrittlement resistance of nickel-based single-crystal superalloy (Ni-SX). The H-charged Ni-SX exhibits severe embrittlement characterized by the appearance of parallel dislocation slip bands and micro-cracks, which could be effectively mitigated through improving the Re content. The segregation behaviors of hydrogen at γ/γ′ interfaces, as captured by hydrogen microprint technique, significantly diminish interfacial cohesion strength by reducing the local atomic bonding strength. Detailed characterizations of bonding charge density highlight that Re plays a crucial role in reducing hydrogen embrittlement susceptibility by suppressing the hydrogen-induced degradation of bonding strength.