Formation of ultra-fine amorphous alloy particles by reduction in aqueous solution

Amorphous alloys are normally prepared as thin ribbons or films by the liquid quench technique or by vapour deposition. Recently we have shown 1 that ultra-fine amorphous Fe–C alloy particles can be prepared by thermal decomposition of Fe(CO) 5 in an organic liquid; that is, by a chemical reaction. Here we report the preparation of small alloy particles by reduction of metal ions by KBH 4 in aqueous solutions. Mössbauer and X-ray diffraction studies show that the particles are amorphous. The amorphous phase is formed because the chemical reaction takes place below the glass transition temperature and because boron atoms are present in the particles. The method may be used for the large-scale production of ultra-fine amorphous alloy particles, which may have applications in ferrofluids, magnetic memory systems and catalysis.