Effect of Nb content on the oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys

Wu Kai; Mei-Hua Kung; Wei-Lin Chen; Rong-Tan Huang; Kuan-Che Lan; Wei-Bing Wang; Ji-Jung Kai; Jun-Hua Luan

doi:10.1016/j.jallcom.2026.187346

Effect of Nb content on the oxidation of Nb_xTiAlCrSi light-weight refractory high-entropy alloys

Wu Kai^*
, Mei-Hua Kung
, Wei-Lin Chen
, Rong-Tan Huang
, Kuan-Che Lan
, Wei-Bing Wang
, Ji-Jung Kai^*
, Jun-Hua Luan

^*Corresponding author for this work

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

Abstract

The oxidation of Nb_xTiAlCrSi light-weight refractory high-entropy alloys (RHEAs) (where x = 0, 0.5, 1.0, and 1.5 mol) was investigated at 950 °C in various He-O₂ mixed gases. The oxidation kinetics of all alloys followed the parabolic-rate law, with their oxidation rates increasing with increasing Nb content and oxygen content. The scales formed on the alloys strongly depended on Nb content. TiO₂ intermixed with Al₂O₃ and SiO₂ was observed on the Nb-free alloy, while Nb₂O₅ was additionally detected on Nb-containing alloys, whose amount strongly increased with Nb content. The formation of highly defective Nb₂O₅ in the 1 Nb and 1.5 Nb alloys was responsible for the significantly faster oxidation rates compared to Nb-free and 0.5 Nb RHEAs. © 2026 Elsevier B.V.

Original language	English
Article number	187346
Journal	Journal of Alloys and Compounds
Volume	1061
Online published	15 Mar 2026
DOIs	https://doi.org/10.1016/j.jallcom.2026.187346
Publication status	Published - 5 Apr 2026

Funding

The authors are thankful for the financial support from the National Science and Technology Council of the Republic of China under Grant Nos. NSTC-113-2221-E-019-014, NSTC-114-2221-E-019-052, and NSTC-114-2224-E-131-001. Prof. Wu Kai is also indebted to the partial funding support by the Hong Kong Research Grant Council under Grant Nos. CityU C1017-21G, 11209021, and 11214423 for TEM analyses. The City University of Hong Kong supported APT equipment under the Grant Nos. 9360161 and 9600011 are also acknowledged. TGA equipment supported by the National Taiwan Ocean University under Grant No. NTOU-RD972-04-03-01 is greatly appreciated.

Research Keywords

Al2O3
Nb2O5
NbxTiAlCrSi refractory high-entropy alloys
SiO2
TiO2

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10.1016/j.jallcom.2026.187346

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title = "Effect of Nb content on the oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys",

abstract = "The oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys (RHEAs) (where x = 0, 0.5, 1.0, and 1.5 mol) was investigated at 950 °C in various He-O2 mixed gases. The oxidation kinetics of all alloys followed the parabolic-rate law, with their oxidation rates increasing with increasing Nb content and oxygen content. The scales formed on the alloys strongly depended on Nb content. TiO2 intermixed with Al2O3 and SiO2 was observed on the Nb-free alloy, while Nb2O5 was additionally detected on Nb-containing alloys, whose amount strongly increased with Nb content. The formation of highly defective Nb2O5 in the 1 Nb and 1.5 Nb alloys was responsible for the significantly faster oxidation rates compared to Nb-free and 0.5 Nb RHEAs. {\textcopyright} 2026 Elsevier B.V.",

keywords = "Al2O3, Nb2O5, NbxTiAlCrSi refractory high-entropy alloys, SiO2, TiO2",

author = "Wu Kai and Mei-Hua Kung and Wei-Lin Chen and Rong-Tan Huang and Kuan-Che Lan and Wei-Bing Wang and Ji-Jung Kai and Jun-Hua Luan",

year = "2026",

month = apr,

day = "5",

doi = "10.1016/j.jallcom.2026.187346",

language = "English",

volume = "1061",

journal = "Journal of Alloys and Compounds",

issn = "0925-8388",

publisher = "Elsevier B.V.",

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TY - JOUR

T1 - Effect of Nb content on the oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys

AU - Kai, Wu

AU - Kung, Mei-Hua

AU - Chen, Wei-Lin

AU - Huang, Rong-Tan

AU - Lan, Kuan-Che

AU - Wang, Wei-Bing

AU - Kai, Ji-Jung

AU - Luan, Jun-Hua

PY - 2026/4/5

Y1 - 2026/4/5

N2 - The oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys (RHEAs) (where x = 0, 0.5, 1.0, and 1.5 mol) was investigated at 950 °C in various He-O2 mixed gases. The oxidation kinetics of all alloys followed the parabolic-rate law, with their oxidation rates increasing with increasing Nb content and oxygen content. The scales formed on the alloys strongly depended on Nb content. TiO2 intermixed with Al2O3 and SiO2 was observed on the Nb-free alloy, while Nb2O5 was additionally detected on Nb-containing alloys, whose amount strongly increased with Nb content. The formation of highly defective Nb2O5 in the 1 Nb and 1.5 Nb alloys was responsible for the significantly faster oxidation rates compared to Nb-free and 0.5 Nb RHEAs. © 2026 Elsevier B.V.

AB - The oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys (RHEAs) (where x = 0, 0.5, 1.0, and 1.5 mol) was investigated at 950 °C in various He-O2 mixed gases. The oxidation kinetics of all alloys followed the parabolic-rate law, with their oxidation rates increasing with increasing Nb content and oxygen content. The scales formed on the alloys strongly depended on Nb content. TiO2 intermixed with Al2O3 and SiO2 was observed on the Nb-free alloy, while Nb2O5 was additionally detected on Nb-containing alloys, whose amount strongly increased with Nb content. The formation of highly defective Nb2O5 in the 1 Nb and 1.5 Nb alloys was responsible for the significantly faster oxidation rates compared to Nb-free and 0.5 Nb RHEAs. © 2026 Elsevier B.V.

KW - Al2O3

KW - Nb2O5

KW - NbxTiAlCrSi refractory high-entropy alloys

KW - SiO2

KW - TiO2

UR - https://www.scopus.com/pages/publications/105032860940

UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-105032860940&origin=recordpage

U2 - 10.1016/j.jallcom.2026.187346

DO - 10.1016/j.jallcom.2026.187346

M3 - RGC 21 - Publication in refereed journal

SN - 0925-8388

VL - 1061

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

M1 - 187346

ER -

Effect of Nb content on the oxidation of Nb_xTiAlCrSi light-weight refractory high-entropy alloys

Abstract

Funding

Research Keywords

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GRF: Irradiation Resistance and Microstructural Stability of Chemically Complex Intermetallic Alloys

ResFac: Inter-University 3D Atom Probe Tomography Unit

ResCtrs: College of Engineering Research Centre for Advanced Nuclear Safety and Sustainable Development (ANSD)

Cite this

Effect of Nb content on the oxidation of NbxTiAlCrSi light-weight refractory high-entropy alloys

Abstract

Funding

Research Keywords

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Other Files and Links

Fingerprint

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GRF: Irradiation Resistance and Microstructural Stability of Chemically Complex Intermetallic Alloys

ResFac: Inter-University 3D Atom Probe Tomography Unit

ResCtrs: College of Engineering Research Centre for Advanced Nuclear Safety and Sustainable Development (ANSD)

Cite this

Effect of Nb content on the oxidation of Nb_xTiAlCrSi light-weight refractory high-entropy alloys