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, Mg\Mo0.7W0.3O4, and Ca\Mo0.7W0.3O4 compounds in the temperature range 750-880 degrees 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 Ca\Mo0.7W0.3O4 and Mg\Mo0.7W0.3O4 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 m(2)/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.