Surface nanocrystallization by mechanical punching process for improving microstructure and properties of Cu-30Ni alloy
(1. School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing 211167, China;2. Department of Chemical and Materials Engineering, University of Alberta, Edmonton, T6G 2G6, Canada)
Abstract: A punching process was employed to produce nanocrystalline on the surface of Cu-30Ni alloy. Compared with the original sample, corresponding changes of the grain size, mechanical properties and corrosion resistance of surface nanocrystalline induced by punching process were characterized by atomic force microscopy, nanoindentation, microhardness, electrochemical behavior and electron work function. It was observed that the grain size was about 40 nm in the topmost surface. The increasing mechanical properties were also demonstrated. Additionally, the dynamic polarization test showed that the surface nanocrystallization improved the resistance to electrochemical attacks. Such increasing corrosion resistance was identified with the higher EWF value. This study demonstrates that surface nanocrystallization can be generated by punching process, and thus mechanical properties and corrosion resistance of alloy can be improved.
Key words: Cu-30Ni alloy; mechanical punching; surface nanocrystallization; mechanical properties; corrosion resistance