Tribo-driven evolution of specific nano-heterostructures to achieve exceptional wear resistance in composites

A novel NiAlTa/cBN composite produced by spark plasma sintering exhibited exceptional wear resistance, which is attributed to the tribo-layers with special nano-heterostructures. At room temperature, an extremely low wear rate (10⁻⁷ mm³·N⁻¹·m⁻¹) and a low coefficient of friction (0.252) of the composite were attributed to the nanoscale amorphous tribo-layer. Amorphization was synergistically controlled by the solid-state amorphization and oxidation processes. The amorphous tribo-layer accommodated the sliding-induced elastic–plastic deformation and virtually eliminated wear. At high temperatures, the plastic incompatibility and strain localization of the subsurface nanocrystalline layer increased the wear rate. The formation of an amorphous tribo-oxide layer and oxidative cleaving effect reduced the fracture toughness of cBN particles and increased the tendency of crack nucleation and growth. Multiple deformation pathways synergistically increased the microplastic deformability of cBN particles and reduced the wear rate. Ta₃N₅ nanoparticles generated by tribo-chemical reactions played a load-supporting and stress-transferring role in sliding wear. A strategy to achieve exceptional wear resistance by regulating the evolution of specific nano-heterostructures on the composite surfaces was proposed.