Reduction, sintering and mechanical properties of rhenium-tungsten compounds

Highlights: • The morphology of W-Re powders can be mainly tuned by the first stage reduction temperature. • Both experimental and calculation results indicate that rhenium promotes the reduction of WO₃. • The closed porosity of W-75 wt%Re pellet is correlated to the vapor pressure of Re. • The Vickers hardness of the Re-W pellet is in the order of Re_0.25W_0.75>ReW > Re₃W. Porous tungsten-rhenium powders with various compositions were prepared by a spray drying method combined with two-stage hydrogen reduction. Using the W-Re powders, W-Re alloy substrates were successfully fabricated by high temperature sintering under the protection of hydrogen. X-ray diffraction analysis, thermogravimetric analysis and temperature programmed reduction were carried out to study the reduction behavior of the tungsten and rhenium containing precursor powders prepared by spray drying. It reveals that the first stage reduction temperature has a significant impact on the microstructure of the W-Re powders. Rhenium in the mixed powder affects the reduction behavior of WO₃. Properties of the W-Re alloy matrices, including relative density, open porosity, mechanical characteristics and electronic structures are also investigated. The first-principles calculation method proved that rhenium reduces the reduction barrier of WO₃, and W-Re compounds obtained in this study are suggested to be a ductile material.