A simple technique of nanocrystallizing metallic surfaces for enhanced resistances to mechanical and electrochemical attacks

Surface nanocrystallization is an effective approach that can be used to enhance many metallic materials for increased resistances to electrochemical and mechanical attacks. Efforts have been continuously made to improve existing surface nanocrystallization processes for feasible industrial applications. In this article, we demonstrate a simple process for surface nanocrystallization achieved by repeated punching with subsuent recovery treatment. As a sample study, we applied this process to a Cu-30Ni alloy and showed that the nanocrystallized Cu-Ni surfaces exhibited increased hardness, corrosion resistance and electron stability; the properties were further improved by increasing the punching time, which led to smaller nano-sized grains and thicker nanocrystalline layers. This study demonstrates that the repeated punching plus recovery treatment is a simple and effective process for surface nanocrystallization.