Fabrication of W-Cu/Mo-Cu functionally graded materials by explosive consolidation

Attempts are made to use explosive consolidation to fabricate high quality W-Cu/Mo-Cu FGMs. Tungsten powder with 99{\%}purity and a particle size of 3$\sim$25$\mu$m and molybdenum/copper powder with $\ge $99{\%} purity and a particle size of 74$\mu$m are used as starting powder. A novel technique, called bidirectional underwater shockwave explosive consolidation, is developed. Two water chambers are placed in both sides of the sample. Detonation-generated shock waves are attenuated by the water chambers before acting on the samples. Through adjusting the height of the water columns, the applied pressure can be adjusted. A self-propagating reaction system is used to provide temperature compensation and to enhance consolidation quality. Flash X-ray photography is used to observe the process of explosive consolidation. Various techniques are used to characterize the recovered samples including optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy spectrum analysis, hardness measurement and density measurement. The explosive consolidation methods developed in the paper can be used to other hard-to-consolidate powder materials.