Ultrahigh cavitation erosion resistant metal-matrix composites with biomimetic hierarchical structure

Cavitation erosion significantly impairs the serviceability of hydroelectric turbines and causes tremendous economic loss. Therefore, the demand for materials with effective resistance to cavitation erosion is imperative. Here, a novel nickel (Ni)-tungsten carbide (WC) composite coating with biomimetic hierarchical structure (BHS) is proposed. The BHS imitates cuttlebone in microscale and abalone nacre in nanoscale. In microscale, a three-dimensional cross-linking eutectic network of Ni-WC sandwiches divides Ni matrix into many small cells, which effectively inhibits crack propagation to an individual cell, controlling the damage caused by cavitation erosion. In nanoscale, numerical modelling results further reveal that the Ni-WC sandwiches can reduce the tensile stress triggered by cavitation impact and dissipate the impact energy, giving rise to ultrahigh cavitation erosion resistance behaviour. The design of similar structures may promote the development of other metal-matrix composites, establishing new methods for developing material systems with advanced properties.