Preferential interdendritic oxidation of laser additively manufactured Inconel 718

[Display omitted] •Preferential interdendritic oxidation of additively manufactured Inconel 718 is observed.•Refined external chromia scale is formed due to elemental segregation.•A high oxygen partial pressure along the interdendritic region is established.•Both transient and diffusion-controlled o...

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Bibliographic Details
Published in:Corrosion science 2021-02, Vol.179, p.109144, Article 109144
Main Authors: Luo, Guoyun, Cheng, Manping, Zhao, Longzhi, Tang, Yanchuan, Yao, Jianhua, Cui, Hailong, Song, Lijun
Format: Article
Language:English
Subjects:
Additive manufacturing
Carbides
Depletion
External pressure
Interdendritic oxidation
Interlayers
Laser deposition
Laves phase
Nickel alloys
Nickel base alloys
Niobium oxides
Oxidation
Partial pressure
Precipitates
Reaction kinetics
Segregation
Superalloys
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Summary:[Display omitted] •Preferential interdendritic oxidation of additively manufactured Inconel 718 is observed.•Refined external chromia scale is formed due to elemental segregation.•A high oxygen partial pressure along the interdendritic region is established.•Both transient and diffusion-controlled oxidation kinetics are enhanced.•Preferential interdendritic oxidation accounts for more than 60 % of mass gain. Preferential interdendritic oxidation of as-built additively manufactured Inconel 718 is observed. Interdendritic depletion of Cr and enrichment of Ti are responsible for a slow formation of fine-grain Cr2O3 external scale that aids the establishment of a high-level oxygen partial pressure along the interdendrtic region. Incomplete oxidation of carbides results in a large volume expansion. Oxidation of Laves phases leads to a discontinuous NbO interlayer that facilitates countercurrent diffusion channels. Preferential interdendritic oxidation dramatically promotes oxidation kinetics of both transient- and diffusion-controlled stages. Measures to homogenize the composition and to control the primary precipitates are desired to improve the oxidation performance.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2020.109144