Impurity Effect on Wear Resistance of Ultrafine-Grained Copper

The wear properties of ultrafine-grained (UFG) Cu samples of different purities were investigated in comparison with the coarse-grained (CG) Cu. The UFG Cu samples, prepared by means of plastic deformation via quasi-static compression, exhibit an enhanced wear resistance relative to the CG Cu samples. For both the UFG and the CG Cu samples, wear volumes increase at higher purities. A steady state worn subsurface structure was formed in each sample after sliding for 60 min, consisting of a heavily deformed nanostructured mixing layer (NML) on top of a continuous dynamic recrystallization (DRX) layer. A pronounced correlation is identified that wear volume increases monotonically with an increasing grain size of the DRX layer. The impurity level of the Cu samples has an obvious influence on the DRX grain sizes, which in turn determines the wear resistance of the Cu samples.