September_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 2 0 2 8 reduces resistance against pitting cor- rosion in chloride environments [16,17] . This effect is related to localized galvan- ic corrosion, in which pits are formed in the vicinity of Cu precipitates. There- fore, one must limit the amount of Cu introduced into stainless steels to min- imize pitting corrosion. CONCLUDING THOUGHTS Metallurgists rarely cross into the domain of biosciences and public health. The COVID-19 pandemic may serve as a trigger for those in the field to reflect on how to contribute. Given the demonstrated antimicrobial activi- ty of Cu, it is incumbent upon materials scientists to design potent antimicrobi- al copper-containing stainless steels as an economical drop-in replacement for traditional stainless steels. To achieve antimicrobial potency comparable to pure Cu, one must design the alloy to contain the maximum volume fraction of nanometer-size Cu precipitates. Do- ing so with as little Cu as possible will not only minimize cost, but also avoid embrittlement and boost corrosion per- formance. Although these conflicting requirements are daunting, the chal- lenge can be met by employing modern computational and simulationmethods along with experimental validation. As presented in this commentary, some of these methods were used to demonstrate the chemical reactivity of Cu step atoms on surfaces of nano- meter-size precipitates in generating reactive oxygen species considered to be important in antimicrobial ac- tion. Equally important, Cu-precip- itation-strengthened steels were fabricated with a high number densi- ty of nanometer-size Cu precipitates at modest Cu concentrations, with prom- ising results regarding antibacterial activity and excellent potential in nu- merous applications. ~AM&P Formore information: Yip-Wah Chung, professor, Department of Materials Sci- ence and Engineering, Northwestern University, 2220 N. Campus Drive, Evan- ston, IL 60208; ywchung@northwest- ern.edu. References 1. H.T. Michels and C.A. Michels, Can Copper Help Fight COVID-19, Adv. Mater. Process, Vol 178, No. 4, p 21-24, 2020. 2. ASTM E2149-13a, Standard Test Method for Determining the Anti- microbial Activity of Antimicrobial Agents Under Dynamic Contact Conditions, ASTM International, West Conshohocken, PA, 2013. 3. M. Bahmani-Oskooee, et al., Cu- bearing, Martensitic Stainless Steels for Applications in Biological Envi- ronments, Mater. Design, Vol 130, p 442-451, 2017. 4. T. Xi, et al., Effect of Copper Addition on Mechanical Properties, Corrosion Resistance and Antibacterial Property of 316L Stainless Steel, Mat. Sci. Eng. C, Vol 71, p 1079-1085, 2017. 5. K. Yang and M. Lu, Antibacterial Properties of an Austenitic Antibacterial Stainless Steel and its Security for Human Body, J. Mat. Sci. Technol., Vol 23, p 333-336, 2007. 6. I.T. Hong and C.H. Koo, Antibacterial Properties, Corrosion Resistance and Mechanical Properties of Cu-Modified SUS 304 Stainless Steel, Mat. Sci. Eng. A, Vol 393, p 213-222, 2005. 7. H. Chai, et al., Antibacterial Effect of 317L Stainless Steel Contained Copper in Prevention of Implant-Related Infect- ion in Vitro and in Vivo, J. Mat. Sci: Mater Med, Vol 22, p 2525-2535, 2011. 8. N. van Doremalen, et al., Aerosol and Surface Stability of SARS-Cov-2 as Compared with SARS-CoV-1, N. Engl. J. Med., Vol 382, p 1564-1567, 2020. 9. R. Hong, et al., Membrane Lipid Peroxidation in Copper Alloy-Mediated Contact Killing of E. coli, Appl. Environ. Microbiol., Vol 78, p 1776-1784, 2012. 10. X. Zhang, et al., Bactericidal Behavior of Cu-containing Stainless Steel Surfaces, Appl. Surf. Sci., Vol 258, p 10058-10063, 2012. 11. M.I. Baena, et al., Bactericidal Activity of Copper and Niobium- Alloyed Austenitic Stainless Steel, Curr. Microbiol., Vol 53, p 491-495, 2006. 12. M.E. Fine, et al., A New Paradigm for Designing High-Fracture-Energy Steels, Metall. Mater. Trans. A, Vol 41, p 3318-3325, 2010. 13. M. Kapoor, et al., Aging Char- acteristics and Mechanical Properties of 1600 MPa Body-Centered Cubic Cu and B2-NiAl Precipitation-Strengthened Fer- ritic Steel, Acta Mater., Vol 73, p 56-74, 2014. 14. M. Kapoor, et al., Effects of Increased Alloying Element Content on NiAl-type Precipitate Formation, Loading Rate Sensitivity, and Ductility of Cu- and NiAl-precipitation-strengthened Ferritic Steels, Acta Mater., Vol 104, p 166-171, 2016. 15. B.E. Wilde and N.D. Greene, Jr., The Variable Corrosion Resistance of 18Cr-8Ni Stainless Steels: Behavior of Commercial Alloys, Corrosion, Vol 25, p 300-306, 1969. 16. J. Banas and A. Mazurkiewicz, The Effect of Copper on Passivity and Corrosion Behavior of Ferritic and Ferritic-Austenitic Stainless Steels, Mat. Sci. Eng. A, Vol 277, p 183-191, 2000. 17. H.M.L. Ferreira de Lima, et al., The Effect of Copper Addition on the Corrosion Resistance of Cast Duplex Stainless Steel, J. Mater. Res. Technol., Vol 8, p 2101-2109, 2019. Lead image: 2019-nCoV spike protein, courtesy of Jason McLellan/University of Texas at Austin.