Alloying Elements and Their Impacts

Alloying elements are added to improve mechanical and electrochemical properties of the metal. For exanple, it is a well-known practice to add chromium to steel to increase its corrosion resistance. However, alloying elements can sometimes have other inpacts as well they may affect the way the metal responds to the environment from a microbial corrosion point of view. 

For instance, it has been reported [16] that by increasing the sulphur content as an alloying element, the likelihood of tubercle formation also increases, and that molybdenum can reduce bacterial viability [17]. Lopes et al. investigated the factors that can help adhesion of Desulfovibrion desulfuricam on metallic and non-metallic surfaces [18]. They showed that adhesion of this group of SRB on nickel surfaces is relatively more significant compared to stainless steel 304 or polymethylmethacrylate (PMMA) surfaces, implying that the bacteria did show a powerful tendency to colonise on nickel surfaces. 

The above shows just a few examples of possible enhanced interactions between the bacteria and some alloying elements. It is still not well known what the real mechanism(s) behind such behaviour could be. Whether such behaviour is the result of some sort of chemical response, the production of adhesion proteins [18], or any other mechanism(s), the end result is that some alloying elements do have some impact on MIC that will make the use of the material containing those alloying elements a matter of caution where the risk of MIC is involved. 

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