Preparation of Molybdenum–Tungsten Alloy Powders via Magnesium and Calcium Vapor Reduction of Oxide Compounds

We report the preparation of molybdenum–tungsten alloy powders via magnesium and calcium vapor reduction of the Mo0.3W0.7O3, MgМо0.7W0.3O4, and CaМо0.7W0.3O4 compounds in the temperature range 750–880°C at residual pressures in the reactor from 5 to 15 kPa. The specific surface area of the Mo–W alloy powders prepared by reducing Mo0.3W0.7O3 slightly exceeds that of the mixture of metal powders obtained by reducing a mixture of WO3 and MoO3 under similar conditions. The specific surface area of the Mo–W alloy powders prepared via magnesium vapor reduction of the CaМо0.7W0.3O4 and MgМо0.7W0.3O4 compounds exceeds that in the case of calcium vapor reduction. We have obtained molybdenum–tungsten alloy powders having lattice parameters of 0.3153 ± 0.0001 and 0.3160 ± 0.0001 nm and ranging in specific surface area from 9 to 22 m2/g. The average crystallite size of the alloys, evaluated using the Scherrer formula, lies in the range 12–35 nm. The powders have a mesoporous structure.