High hardness and wear resistance of W-Cu composites achieved by elemental dissolution and interpenetrating nanostructure.

The effects of aluminum (Al) on the microstructure, hardness and wear resistance of tungsten-copper (W-Cu) composites were investigated. The W-Cu composites were fabricated via mechanical alloying and spark plasma sintering. It is found that the Al dissolved in the metastable W-Cu alloy can act as an 'intermediary' to hinder the diffusion and phase separation process of Cu out of W during sintering, constructing an interpenetrating nanostructure where Al redistributes in W and Cu. Correspondingly, the hardness of composites increase from 463.4 HV to 512.05 HV due to Al dissolution and formation of the nanostructure, and their contributions to hardness variation of the original W and Cu regions were distinguished by nanoindentation. In addition, the wear volume was also reduced to less than a third of that of original W-Cu composites without Al addition due to the abundant interfaces and mechanical strengthening, which restricts the removal of W and propagation of cracks during the wear process.