Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs) possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

Corrosion-Resistant High-Entropy Alloys: A Review

Corrosion of Al xCoCrFeNi high-entropy alloys: Al-content and potential scan-rate dependent pitting behavior

The evolution of corrosion pits on stainless steel immersed in chloride solution occurs in three distinct stages: nucleation, metastable growth and stable growth. This paper describes the growth of metastable corrosion pits on stainless steel immersed in chloride solution, and their transition to stability. The rate of growth of individual corrosion pits is controlled by diffusion of the dissolving metal cations from the pit interior, the surface of which is saturated with the metal chloride. This process is independent of electrode potential. Analysis of the diffusion yields a critical value of the product of the pit radius and its dissolution current density (termed the ‘pit stability product’) below which the pit is metastable and may repassivate, and above which the pit is stable. The critical value of the pit stability product for stainless steel in chloride solution is 0.3 A m -1 . All pits, whether metastable, or destined to become stable, grow initially in the metastable condition, with a pit stability product which increases linearly with time, but below the critical value. Metastable growth requires a perforated cover over the pit mouth to provide an additional barrier to diffusion, enabling the aggressive pit anolyte to be maintained. In this state pits grow at a constant mean current density which is maintained by periodic partial rupture of the cover. Stable pit growth is then achieved when the cover is no longer required for continued propagation, and the pit depth is itself a sufficient diffusion barrier; stability is characterized by a constant mean pit stability product above the critical value. If the cover is lost prematurely, before the critical pit stability product is achieved, the pit anolyte is diluted and repassivation is inevitable. In contrast to the growth rate of individual pits, the distribution of pitting current transients is dependent on electrode potential: the pit nucleation site, particularly its geometry, is exclusively responsible for this potential distribution. It is proposed th at shallower, more-open sites are activated only at higher potential and higher current density, and are consequently more likely to achieve stability.

Metastable pitting corrosion of stainless steel and the transition to stability

Passivity breakdown, pit initiation and propagation of pits in metallic materials – Review

In the past 14 years, as a branch of high-entropy alloy (HEA) materials, HEA films and coatings have exhibited the attractive and unique properties, relative to the conventional film and coating ma...

https://www.tandfonline.com/doi/pdf/10.1080/21663831.2018.1434248

Microstructures and properties of high-entropy alloy films and coatings: a review

A study on the corrosion behavior of aluminum alloys in seawater

Localized corrosion of stainless steels (SSs) has often occurred in newsprint paper machines, despite the low chloride concentration in the process water. This is now known to be caused by...

Hosni M. Ezuber

Papers

A study on the corrosion behavior of aluminum alloys in seawater

Pitting of Stainless Steels by Thiosulfate Ions

Effects of sigma phase precipitation on seawater pitting of duplex stainless steel

Influence of temperature and thiosulfate on the corrosion behavior of steel in chloride solutions saturated in CO2

An experimental confirmation of the pitting potential model of galvele