Abstract

A simple processing route to cobalt–molybdenum and cobalt–tungsten intermetallics (Co_xM_y, where M = Mo and W, and x∶y = 3∶1 and 7∶6) has been developed, on the basis of the use of precursors resulting from freeze-drying of aqueous solutions of the appropriate common metal salts. The influence of the preparative variables on the outcomes of this procedure is examined. These compounds are prepared as single phases by thermal reduction of amorphous freeze-dried powders under a hydrogen–argon atmosphere (8% H₂), followed by slow cooling of the samples. The materials have been characterised by X-ray powder diffraction, metal analysis, scanning electron microscopy and thermogravimetry under an oxygen flow. Co_xMo_y and Co_xW_y grains are aggregates of submicrometric spherical particles.