Subsurface microstructural changes of alloy 625 related to oxidation at 900 °C in lab air and humid air
Abstract
Alloy 625 was oxidized at 900 °C in lab air and in air + 20%vol. H 2 O for 400 h to estimate the microstructural changes experienced by the alloy during exposure at high temperature. The specimen mass loss in air + 20%vol. H 2 O evolved linearly after a very short period of exposure due to the formation of volatile species from the protective Cr 2 O 3 layer. The chromium loss rate was in the order of 5.5 × 10 −7 mg.cm -2 .s -1 (evaluated by direct mass variation measurements) and 7.5 × 10 −7 mg.cm -2 .s -1 (evaluated from Cr-mass balance) in air + 20%vol. H 2 O in the present conditions. Pronounced chemical and microstructural changes were observed in the subsurface for samples exposed in air + 20%vol. H2O. The recession of the alloy interface due to chromium removal was insufficient to explain the pronounced accumulation of δ-Ni 3 (Nb,Mo) phase at the alloy-oxide interface, demonstrating the significant uphill diffusion of Nb. Chemical breakaway on the sample edges involved the oxidation of δ-Ni 3 (Nb,Mo) phase, forming powdery oxides.
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BibTeX
@article{jacquard2026subsurface,
title = {{Subsurface microstructural changes of alloy 625 related to oxidation at 900 °C in lab air and humid air}},
author = {B. Jacquard and S. Mathieu and G. Steciuk and S. Migot and D. Bonina and T. Perez and Enrica Epifano and Daniel Monceau and Aurélie Vande Put},
journal = {Corrosion Science},
year = {2026},
month = oct,
doi = {10.1016/j.corsci.2026.113815},
url = {https://hal.science/hal-05836571v1},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Subsurface microstructural changes of alloy 625 related to oxidation at 900 °C in lab air and humid air
AU - B. Jacquard
AU - S. Mathieu
AU - G. Steciuk
AU - S. Migot
AU - D. Bonina
AU - T. Perez
AU - Enrica Epifano
AU - Daniel Monceau
AU - Aurélie Vande Put
PY - 2026
DA - 2026/10/23
JO - Corrosion Science
DO - 10.1016/j.corsci.2026.113815
UR - https://hal.science/hal-05836571v1
AB - Alloy 625 was oxidized at 900 °C in lab air and in air + 20%vol. H 2 O for 400 h to estimate the microstructural changes experienced by the alloy during exposure at high temperature. The specimen mass loss in air + 20%vol. H 2 O evolved linearly after a very short period of exposure due to the formation of volatile species from the protective Cr 2 O 3 layer. The chromium loss rate was in the order of 5.5 × 10 −7 mg.cm -2 .s -1 (evaluated by direct mass variation measurements) and 7.5 × 10 −7 mg.cm -2 .s -1 (evaluated from Cr-mass balance) in air + 20%vol. H 2 O in the present conditions. Pronounced chemical and microstructural changes were observed in the subsurface for samples exposed in air + 20%vol. H2O. The recession of the alloy interface due to chromium removal was insufficient to explain the pronounced accumulation of δ-Ni 3 (Nb,Mo) phase at the alloy-oxide interface, demonstrating the significant uphill diffusion of Nb. Chemical breakaway on the sample edges involved the oxidation of δ-Ni 3 (Nb,Mo) phase, forming powdery oxides.
SN - 0010-938X
SN - 1879-0496
ER -