Oxidation behavior and condition-specific (Nb, X)Si
5 affiliations
- 1Department of Materials Science and Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea; Jinhap, Co., Daejeon, 34302, Republic of Korea
- 2Department of Materials Science and Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea
- 3Department of Materials Science and Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea; Advanced Materials & Processing Center, Institute for Advanced Engineering, Yongin, 17180, Republic of Korea
- 4Jinhap, Co., Daejeon, 34302, Republic of Korea
- 5Department of Materials Science and Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea; Corresponding author.
Abstract
In this study, the oxidation behavior and (Nb, X)Si 2 depletion behavior under isothermal oxidation at 1500 °C in ambient air were investigated for a silicide-coated Nb–16Si–22Ti–5Cr–3Al (at.%) alloy using separate specimens for each oxidation duration. Pack cementation produced an (Nb, X)Si 2 layer (X = Ti, Cr, Al) with an average thickness of approximately 104 μm on the alloy surface. During oxidation, the coating evolved into a SiO 2 /TiO 2 -rich surface scale, an intermediate (Nb, X)Si 2 + (Nb, X) 5 Si 3 region, and an inner (Nb, X) 5 Si 3 layer. The uncoated alloy suffered severe degradation, showing a mass change of −350.5 mg/cm 2 after 20 h. By contrast, the silicide-coated alloy maintained a low mass change of 2.7 mg/cm 2 after 20 h, confirming effective surface protection within the stable regime. A phase-fraction-based analysis of cross-sectional BSE images showed that the retained (Nb, X)Si 2 area fraction decreased linearly with oxidation time, giving an estimated (Nb, X)Si 2 depletion time of ∼22.4 h under the present oxidation condition. After 23 h, the coated alloy showed rapid mass loss (−238.8 mg/cm 2 ) and substrate oxidation, which occurred near the estimated depletion time of the protective (Nb, X)Si 2 phase. These findings demonstrate that the silicide coating can provide short-term oxidation protection for the Nb–16Si–22Ti–5Cr–3Al alloy under the specific 1500 °C condition investigated here, and the phase-fraction analysis provides a condition-specific (Nb, X)Si 2 depletion-time estimate under the present oxidation condition.
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BibTeX
@article{oh2026oxidation,
title = {{Oxidation behavior and condition-specific (Nb, X)Si}},
author = {Jungseok Oh and Sunjin Kim and Jini Park and Hayeong Yang and Jeong-Muk Choi and Sangyeob Lee and Choong-Heui Chung and Joon-Sik Park},
journal = {Applied Surface Science Advances},
year = {2026},
month = oct,
doi = {10.1016/j.apsadv.2026.101066},
url = {https://doi.org/10.1016/j.apsadv.2026.101066},
note = {CC BY},
}
RIS
TY - JOUR
TI - Oxidation behavior and condition-specific (Nb, X)Si
AU - Jungseok Oh
AU - Sunjin Kim
AU - Jini Park
AU - Hayeong Yang
AU - Jeong-Muk Choi
AU - Sangyeob Lee
AU - Choong-Heui Chung
AU - Joon-Sik Park
PY - 2026
DA - 2026/10/24
JO - Applied Surface Science Advances
DO - 10.1016/j.apsadv.2026.101066
UR - https://doi.org/10.1016/j.apsadv.2026.101066
AB - In this study, the oxidation behavior and (Nb, X)Si 2 depletion behavior under isothermal oxidation at 1500 °C in ambient air were investigated for a silicide-coated Nb–16Si–22Ti–5Cr–3Al (at.%) alloy using separate specimens for each oxidation duration. Pack cementation produced an (Nb, X)Si 2 layer (X = Ti, Cr, Al) with an average thickness of approximately 104 μm on the alloy surface. During oxidation, the coating evolved into a SiO 2 /TiO 2 -rich surface scale, an intermediate (Nb, X)Si 2 + (Nb, X) 5 Si 3 region, and an inner (Nb, X) 5 Si 3 layer. The uncoated alloy suffered severe degradation, showing a mass change of −350.5 mg/cm 2 after 20 h. By contrast, the silicide-coated alloy maintained a low mass change of 2.7 mg/cm 2 after 20 h, confirming effective surface protection within the stable regime. A phase-fraction-based analysis of cross-sectional BSE images showed that the retained (Nb, X)Si 2 area fraction decreased linearly with oxidation time, giving an estimated (Nb, X)Si 2 depletion time of ∼22.4 h under the present oxidation condition. After 23 h, the coated alloy showed rapid mass loss (−238.8 mg/cm 2 ) and substrate oxidation, which occurred near the estimated depletion time of the protective (Nb, X)Si 2 phase. These findings demonstrate that the silicide coating can provide short-term oxidation protection for the Nb–16Si–22Ti–5Cr–3Al alloy under the specific 1500 °C condition investigated here, and the phase-fraction analysis provides a condition-specific (Nb, X)Si 2 depletion-time estimate under the present oxidation condition.
SN - 2666-5239
ER -