A percolation theory for designing corrosion-resistant alloys

Iron-chromium and nickel-chromium binary alloys containing sufficient quantities of chromium serve as the prototypical corrosion-resistant metals owing to the presence of a nanometre-thick protective passive oxide film(1-8). Should this film be compromised by a scratch or abrasive wear, it reforms with little accompanying metal dissolution, a key criterion for good passive behaviour. This is a principal reason that stainless steels and other chromium-containing alloys are used in critical applications ranging from biomedical implants to nuclear reactor components(9,10). Unravelling the compositional dependence of this electrochemical behaviour is a long-standing unanswered question in corrosion science. Herein, we develop a percolation theory of alloy passivation based on two-dimensional to three-dimensional crossover effects that accounts for selective dissolution and the quantity of metal dissolved during the initial stage of passive film formation. We validate this theory both experimentally and by kinetic Monte Carlo simulation. Our results reveal a path forward for the design of corrosion-resistant metallic alloys. A percolation theory of alloy passivation is developed accounting for selective dissolution and the quantity of metal dissolved during the primary passivation process, which provides a quantitative way for designing corrosion-resistant alloy compositions.

Automated summary

The text introduces a percolation theory of alloy passivation, explaining the relationship between the formation of protective oxide film and alloy composition, providing a quantitative method for designing corrosion-resistant metallic alloys.