Hierarchical nanostructured W-Cu composite with outstanding hardness and wear resistance

Hierarchical nanostructured W-Cu composite with an average W size below 200 nm and nanocrystalline structure inside the W phase was obtained by refining the inner structure of the initial ultrafine powders combined with high-pressure spark plasma sintering. It revealed that an atomic scale combination can be formed at both the W grain boundaries and W/Cu interfaces. Accordingly, the nanostructured W-Cu composite exhibits twofold hardness and greatly improved wear resistance with satisfactory electrical conductivity, as compared to those of their fine grain structured counterparts. The upgraded wear resistance is attributed to the restricted micro-plowing and the mechanically mixed layer, induced by a refined microstructure, intrinsic high hardness, and the composition modulation on the wear surface.