Novel Mg alloys with Zn, Ca, and rare earths show reduced galvanic corrosion.

There are a few super corrosion-resistant alloys I have come to know recently, including HEAs such as (TiVNbMoTa)25Ni75 and FeCoNiCrNb0.5, Fe-Cr-Al microalloyed steels, and HCCI alloys.

The answer mostly lies in the desired properties and the environment we are discussing.

A new class of alloys, the so-called high-entropy alloys (HEAs) represent a major class of novel materials designed for superior corrosion resistance in harsh industrial environments, such as chemical processing, marine, and high-temperature settings. These alloys typically consist of multiple principal elements in near-equiatomic ratios, leading to high configurational entropy that stabilizes single-phase structures and promotes stable passive films.

Elements like chromium (Cr), molybdenum (Mo), and nickel (Ni) enhance pitting resistance and passivation, while aluminum (Al) can improve mechanical strength but may reduce resistance in chloride environments if it leads to phase segregation; titanium (Ti) often forms protective TiO2 films but can increase microstructural heterogeneity, potentially promoting localized corrosion. In extreme conditions like high-temperature oxidation or acidic media, HEAs outperform traditional alloys by forming dense, adherent oxide layers.

Other novel compositions include modified stainless steels, aluminum-magnesium alloys, and magnesium-based alloys, often tailored through alloying additions or processing techniques like equal channel angular pressing (ECAP) to refine grains and enhance protective oxide stability.

Some alloys for such applications are:

• (Fe2.25Co1.25Cr)94Al6 (HEA)
• Al0.7CoCrFeNi (HEA, at.%: Al 13.82, Co 21.86, Cr 21.40, Fe 22.13, Ni 20.79)
• CoCrFeNiCu (HEA, at.%: Co 20.66, Cr 19.83, Fe 19.98, Ni 19.40, Cu 20.14)
• 13CrU (Martensitic stainless steel: Based on 13CrS with +0.67 wt% Mo, +1.13 wt% Ni, trace Ta)
• Al-5.5Mg-1.5Zn-0.4Sc
• Mg-Zn-Mn (ZM31, processed via ECAP)
• Fe81Cr15Mo1V2C1 and Fe80Cr15Mo1V3C1 (Cast tool steels, wt%)

I hope this helps!