Surface amorphization and nanocrystallization of the gradient-structured copper by explosive impact treatment

Abstract

In this study, surface treatment on pure copper plates is carried out by an explosive impact technique. The gradient structures were successfully produced along the depth of plates near the impacted surface. It is found that both amorphous state and nano-grains with an approximate size of 10 nm are generated at the topmost surface after explosive impact treatment. The corresponding microhardness at the topmost surface is 4.35 times that of the annealed sample. Moreover, it is found that the microhardness decreases along depth of the specimen gradually. The calculation results demonstrate that amorphization and nanocrystallization on the topmost surface are closely related to the rapid temperature rise and cooling rate. This work provides experimental evidence that the explosive impact treatment is a potential technology of surface treatment to produce a surface amorphous state.