Sintering of molybdenum metal powder using microwave energy

Molybdenum is a refractory metal used for high temperature applications. Sintered molybdenum (Mo) with fine microstructures is desired due to its improved mechanical properties. However, the sintering of Mo is not easily achievable by conventional processes. In this work, the author report the results of sintering molybdenum powder to obtain submicron grain size microstructure using microwave energy. As received Mo powder was agglomerated with a mean agglomerate size of 1˙6 μm, but equivalent surface area based on N₂ adsorption suggests an average particle size of 200 nm. Sintering was carried out using the as received powder. Samples with densities as high as 98% of theoretical density (TD) were obtained with limited grain growth in <5 min of sintering time in microwaves, compared to 10–20 h in a conventional process. The highlight of this research is achieving 98%TD in 1 min at 1650°C with a submicron grain size.