Abstract
Tungsten based W–1C and W–2B4C–1C (wt-%) powders synthesised by mechanical alloying (MA) for milling durations of 10, 20 and 30 h, in wet (ethanol) and dry conditions, were characterised. X-ray fluorescence spectroscopy investigations revealed Co contamination which increased with increasing milling time during wet milling. X-ray diffraction investigations revealed the presence of W and WC phases in all powders, Co3C intermetallic in the wet milled W–1C powders and W2B intermetallic phase in both wet and dry milled W–2B4C–1C powders. As blended and MA processed powders were consolidated into green compacts by uniaxial cold pressing at 500 MPa and solid phase sintered at 1680°C under hydrogen and argon atmospheres for 1 h. X-ray diffraction investigations revealed the presence of W2C intermetallic phase in sintered composites produced from both wet and dry milled W–1C powders and the W2B intermetallic phase in sintered material from the wet milled W–2B4C–1C powder. Sintered composites from wet milled powders showed relative densities >91%, with the maximum density of 99·5% measured for the sintered 30 h wet milled W–2B4C–1C composites. Microhardness values for the wet milled W–1C and W–2B4C–1C composites were 2–2·5 times higher than those for dry milled composite powders. A maximum hardness value of 23·7±2·1 GPa was measured for the sintered W–2B4C–1C composite wet milled for 20 h.