Cavitation erosion of a novel high silicon brass: An EBSD study of a copper-based alloy with hexagonal lattice structure

Cavitation erosion of a lead-free silicon brass (CuZn10Si5Al1) was studied employing ultrasonic cavitation tests. The new alloy exhibits a remarkable resistance against cavitation in comparison with resistant copper-based alloys previously reported by the authors under identical test conditions. In contrast to most copper-based alloys, the tested material mainly consists of a single hexagonal close-packed phase with a negligible fraction of face-centered cubic phase. Electron backscatter diffraction was employed to examine plastic deformation induced by cavitation. This evaluation revealed a strong influence of the grain orientation on the local cavitation resistance. It is noticeable during the incubation stage that, while grain surfaces oriented nearly parallel to the basal plane exhibit visible deformation resulting from twinning, grains with surfaces oriented nearly parallel to prism planes show weak traces of plastic deformation and very low damage induced by cavitation. Additionally, grain boundaries located between grains subjected to large differences in deformation were found to be mostly resistant to cracking or void formation. It is concluded that high crystal anisotropy related to the single-phase hexagonal structure found in the CuZn10Si5Al1 alloy promotes a microstructure with exceptional resistance to cavitation erosion.