Abstract
CoCrFeNiMn high-entropy alloy (HEA) has great potential for engineering application due to its good ductility and high fracture toughness at low temperature. It can be deposited on components as coatings to take advantage of its excellent properties and reduce the cost. In this study, CoCrFeNiMn HEA coatings were deposited on 316L stainless steel substrates by atmospheric plasma spraying (APS) technique, and a series of transient thermal shock tests were performed. It was found that the coatings contained two main phases: a face-centered cubic (FCC) solid solution phase and a flocculent oxides phase. The elemental contents of Co, Cr, Fe, and Ni were close to equal atomic percentage in the coating, while Mn was reduced significantly. The oxygen was mainly distributed in the dark flocculent oxides phase. After transient thermal shock tests, these two phases remained stable, but some tiny cracks appeared on the surface. Meanwhile, the microhardness of the coating after transient thermal shock tests also showed stable, ∼ 420 HV. Weibull statistics were used to analyze the reliability of the microhardness, and the Weibull modulus m was distributed from 9 to 15. The CoCrFeNiMn HEA coating exhibited high phase stability and excellent properties under transient thermal shock, making it have service advantages in extreme environments, especially in the fields of the development of future nuclear and aerospace structural materials.
Highlights
It can be observed that the thickness of the as-sprayed high-entropy alloy (HEA) coatings by atmospheric plasma spraying (APS) is between 300∼400 μm (Figure 3A)
Though an obvious interface is appeared between the HEA coating and the 316L steel substrate, the HEA coating is closely bonded to the substrate (Figure 3B)
After transient thermal shock tests with different electron beams (EBs) power density, the bright phase and flocculent dark phase remain in the HEA coating, and no obvious changes in the distribution of these two phases can be observed, as shown in Figures 3E–P, which indicates that the phase structures of the HEA coating are stable under transient thermal shock by EB
Summary
Based on the ideal solution hypothesis and Boltzmann theory, they proposed the concept of high-entropy alloys (HEA) for the first time (Yeh et al, 2004). HEAs possess excellent properties, such as high hardness, High-Entropy Alloy Coatings high corrosion resistance and high resistivity (Chen et al, 2005; Li et al, 2016; Park et al, 2016; Hsu et al, 2017; Huo et al, 2018; Lei et al, 2018; Lu et al, 2019). These excellent properties caught the researchers’ great attention and made HEA a research hotspot in recent years (Yang et al, 2018; Fan et al, 2020; Ding et al, 2021)
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