High-Temperature Oxidation Behavior of AlTiNiCuCox High-Entropy Alloys

Junfeng Wang; Qiaobai He; Guanqi Liu; Qi Zhang; Guotan Liu; Zhihao Huang; Xiaoshuo Zhu; Yudong Fu

doi:10.3390/ma14185319

High-Temperature Oxidation Behavior of AlTiNiCuCo_x High-Entropy Alloys

Materials (Basel). 2021 Sep 15;14(18):5319. doi: 10.3390/ma14185319.

Authors

Junfeng Wang^{1

2}, Qiaobai He¹, Guanqi Liu¹, Qi Zhang³, Guotan Liu¹, Zhihao Huang¹, Xiaoshuo Zhu⁴, Yudong Fu¹

Affiliations

¹ Department of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China.
² Shanghai Key Lab of Advanced High-Temperature Materials, Precision Forming and State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
³ Chengdu Aircraft Industrial (Group) Co., Ltd., Chengdu 610072, China.
⁴ Department of Mechanical Engineering, Xinjiang University, Urumqi 830046, China.

Abstract

In this study, the high-temperature oxidation behavior of a series of AlTiNiCuCo_x high-entropy alloys (HEAs) was explored. The AlTiNiCuCo_x (x = 0.5, 0.75, 1.0, 1.25, 1.5) series HEAs were prepared using a vacuum induction melting furnace, in which three kinds of AlTiNiCuCo_x (x = 0.5, 1.0, 1.5) alloys with different Co contents were oxidized at 800 °C for 100 h, and their oxidation kinetic curves were determined. The microstructure, morphology, structure, and phase composition of the oxide film surface and cross-sectional layers of AlTiNiCuCo_x series HEAs were analyzed using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD). The influence of Co content on the high-temperature oxidation resistance of the HEAs was discussed, and the oxidation mechanism was summarized. The results indicate that, at 800 °C, the AlTiNiCuCo_x (x = 0.5, 1.0, 1.5) series HEAs had dense oxide films and certain high-temperature oxidation resistance. With increasing Co content, the high-temperature oxidation resistance of the alloys also increased. With increasing time at high temperature, there was a significant increase in the contents of oxide species and Ti on the oxide film surface. In the process of high-temperature oxidation of AlTiNiCuCo_x series HEAs, the interfacial reaction, in which metal elements and oxygen in the alloy form ions through direct contact reaction, initially dominated, then the diffusion process gradually became the dominant oxidation factor as ions diffused and were transported in the oxide film.

Keywords: high-entropy alloy (HEA); high-temperature oxidation resistance; microstructure morphology; oxidation kinetics; phase composition and oxidation mechanism.