Corrosion Properties of High-Entropy Alloys

High-entropy alloys (HEAs) have emerged as a transformative class of metallic materials defined by the near-equiatomic mixing of five or more elements. By harnessing high configurational entropy, these alloys often form simple solid-solution phases rather than conventional intermetallic compounds. This fundamentally alters their corrosion properties, as a homogeneous distribution of multiple principal elements can promote the formation of stable, protective surface films. HEAs have been shown to exhibit strong general corrosion resistance in a variety of aqueous environments, from neutral saline solutions to acidic media, often outperforming traditional stainless steels and nickel-based alloys. Key factors influencing their corrosion behaviour include the choice and proportion of alloying elements (for example, chromium, molybdenum and aluminium), microstructural features (phase composition, grain size and homogeneity), and processing history (casting, heat treatment and additive manufacturing). The capacity of HEAs to form rapid, self-healing passive films under anodic polarisation renders them particularly attractive for applications in marine infrastructure, chemical processing equipment and energy systems. Furthermore, the tunability of elemental combinations opens pathways to design alloys with tailored pitting resistance and reduced susceptibility to localised attack, thereby addressing critical challenges in industrial corrosion management.

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Corrosion Properties of High-Entropy Alloys publication trend

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Technical terms

High-entropy alloy: A metallic alloy composed of five or more elements in near-equiatomic proportions, stabilised by high configurational entropy.

Passive film: A thin, protective oxide or hydroxide layer that forms spontaneously on the alloy surface, inhibiting further corrosion.

Configurational entropy: A thermodynamic quantity reflecting the disorder in the distribution of atoms among lattice sites, which can stabilise simple solid solutions.

Pitting corrosion: A localised form of corrosion leading to the formation of voids or ‘‘pits’’ on a metal surface, often initiated at defects in the passive film.

References

1. Corrosion-Resistant High-Entropy Alloys: A Review. Metals (2017).
2. Corrosion of high entropy alloys. npj Materials Degradation (2017).
3. Alloying and Processing Effects on the Aqueous Corrosion Behavior of High-Entropy Alloys. Entropy (2014).
4. Study of the surface oxides and corrosion behaviour of an equiatomic CoCrFeMnNi high entropy alloy by XPS and ToF-SIMS. Corrosion Science (2020).
5. Corrosion behavior of Hf0.5Nb0.5Ta0.5Ti1.5Zr refractory high-entropy in aqueous chloride solutions. Electrochemistry Communications (2019).