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 Mo 0.3 W 0.7 O 3 , MgМо 0.7 W 0.3 O 4 , and CaМо 0.7 W 0.3 O 4 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 Mo 0.3 W 0.7 O 3 slightly exceeds that of the mixture of metal powders obtained by reducing a mixture of WO 3 and MoO 3 under similar conditions. The specific surface area of the Mo–W alloy powders prepared via magnesium vapor reduction of the CaМо 0.7 W 0.3 O 4 and MgМо 0.7 W 0.3 O 4 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.