Improvement of machinability of tungsten by copper infiltration technique

Infiltration of liquid copper in partially sintered tungsten was undertaken to improve machinability of tungsten. Initial skeleton of tungsten was prepared by pressing commercial tungsten powder in cold isostatic press to near-net shapes. The green compacts are then subjected to controlled sintering to about 85% theoretical density. This leaves adequate amount of open channels which are filled subsequently with liquid copper by infiltration. The resulting composite material exhibits reasonable strength coupled with desired level of machinability. Some pilot samples were made with ∼99% density and were subjected to in-house characterization (e.g., density, shrinkage and porosity). Microstructural study has been carried out to compare the theoretically calculated porosity levels with the observed porosity level. X-ray diffraction studies revealed presence of elemental tungsten and copper with no mutual solubility. Mechanical properties (e.g., ultimate tensile strength, tensile elongation and hardness values) of the composite were also evaluated and reported.