High-Temperature Oxidation Behavior of AlTiNiCuCox High-Entropy Alloys.

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

doi:10.3390/ma14185319

Abstract

In this study, the high-temperature oxidation behavior of a series of AlTiNiCuCox high-entropy alloys (HEAs) was explored. The AlTiNiCuCox (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 AlTiNiCuCox (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 AlTiNiCuCox 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 AlTiNiCuCox (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 AlTiNiCuCox 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.

Highlights

In 2004, Yeh et al [1,2,3] broke away from the design concept of common alloy materials and proposed melting alloys of multiple elements with high mixed entropy, which were called “multi-principal-element high-disorder alloys” and were later referred to as “highentropy alloys (HEAs)”
The results indicated that the oxidation rates of all the oxidized HEAs increase with either increasing temperature or decreasing Al content, and the best oxidation resistance at temperatures of 800, 875, and 950 ◦C was observed with CoCrFeNiAl HEA
The oxidation behavior of AlCoCrFeNi HEA at 1100 ◦C was investigated by Jie Lu et al [13] in 2021

Summary

Introduction

In 2004, Yeh et al [1,2,3] broke away from the design concept of common alloy materials and proposed melting alloys of multiple elements with high mixed entropy, which were called “multi-principal-element high-disorder alloys” and were later referred to as “highentropy alloys (HEAs)”. Y. Garip et al [12] studied the high-temperature oxidation resistance of the CoCrFeNiAlx series HEAs. The results indicated that the oxidation rates of all the oxidized HEAs increase with either increasing temperature or decreasing Al content, and the best oxidation resistance at temperatures of 800, 875, and 950 ◦C was observed with CoCrFeNiAl HEA. The oxidation behavior of AlCoCrFeNi HEA at 1100 ◦C was investigated by Jie Lu et al [13] in 2021 They found that this HEA exhibits an extremely low oxidation rate and shows good resistance to oxide scale spallation. It was found that when the Al content (atomic fraction) is 10%, the oxidation kinetics of the alloy at 1050 ◦C conform to parabolic law [16,17], and the oxidation resistance at high temperature is the best among the various Al contents that were tested

Methods

Results

Conclusion