Distinct effects of in-situ and ex-situ hydrogen charging methods on the mechanical behavior of CoCrFeNi high-entropy alloy fabricated by laser- powder bed fusion

The hydrogen embrittlement behavior of CoCrFeNi high-entropy alloy (HEA) fabricated by laser-powder bed fusion (L-PBF) under ex-situ and in-situ hydrogen charging conditions was investigated. The ex-situ hydrogen pre-charged sample showed excellent resistance to hydrogen embrittlement, whereas in-situ hydrogen charging during tensile testing led to a substantial loss in ductility and prevailing hydrogen-assisted cracking. Such discrepancy was attributed to the enhanced apparent solubility and diffusivity especially at grain boundaries in the in-situ condition. The underlying hydrogen embrittlement mechanisms for the current L-PBF HEA are discussed, through which the critical role of the synergy between mechanical and environmental conditions is highlighted. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the hydrogen embrittlement behavior of CoCrFeNi high-entropy alloy (HEA) fabricated by laser-powder bed fusion (L-PBF) under ex-situ and in-situ hydrogen charging conditions. The ex-situ pre-charged sample showed resistance to hydrogen embrittlement, while in-situ hydrogen charging during tensile testing resulted in a loss in ductility and hydrogen-assisted cracking. The enhanced solubility and diffusivity at grain boundaries in the in-situ condition were attributed to this discrepancy. The study highlights the critical role of the synergy between mechanical and environmental conditions in the hydrogen embrittlement mechanisms of L-PBF HEA.