Amorphous metal powders

Amorphous metal powder that possess a substantial Tx-Tg region (AT), say 50°C, can be consolidated in the super-cooled region to near-full density bulk amorphous metal with one ECAE pass. 

The more extensive studies of reactions based on a sonolytic step were effected in transition metal chemistry, with theoretical and applied values as well. In his pioneering work, Suslick and his group studied essentially metal carbonyl complexes.Further developments in this domain were made in two directions, the complete decomposition of the complexes exploited for the production of amorphous metal powders (pp. 180 and 239), and the selective cleavage of ligands to generate reactive intermediates. 

The oxide monobutyltin oxide [51590-67-1J, is a sesquioxide, C H SnO from which it is difficult to remove the last traces of water. It is an infusible, insoluble, amorphous white powder that forms when butyltin trichloride is hydrolyzed with base. The partially dehydrated material, butylstaimoic acid [2273-43-0] is slightly acidic and forms alkaH metal salts. These salts, ie, alkaH metal alkylstaimonates, form when excess alkaH is used to hydrolyze the organotin trichloride ... 

X [Fe(C5H5)2]2 [Tc8(/i-Br)8Br4JBr2 Black fine needle-like crystals with metallic lustre. Insoluble in orgaic and inorganic solvents but does not decompose. Grinding yields amorphous black powder. 

Bonnemann, EL, Brijoux, W., and Joussen, T., (to Studiengesellschaft Kohle mbH) Microcrystalline-to-amorphous metal and/ or alloy powders dissolved without protective colloid in organic solvents, U.S.Pat, 5, 580,492, 1993. 

SmCl3 resulted in the reduction only to SmC. From NdCl3 + Ca with the addition of Fe powder, the alloy Nd2Fei7 was obtained. In a discussion of the results it was observed that the products obtained at ambient temperature by mechanical alloying are the same which result from the conventional metallothermic reduction of the rare earth halides. However, the metallothermic reduction requires a temperature of 800-1000°C for the reduction of the chlorides and 1400-1600°C for the fluorides. The products of the mechanical process, on the other hand, are fine, amorphous or microcrystalline, highly reactive metal powders mixed with CaCl2. 

Boron does not react with water at ambient temperatures. The powdered amorphous form, however, reacts slowly at 100°C producing horic acid. The amorphous metal reacts slowly with dilute mineral acids at ambient temperatures the crystalline form is inert. The former, however, reacts vigorously with concentrated nitric acid. The amorphous powder ignites in oxygen at... 

When one component of a bimetallic alloy is leached out, a finely divided metal powder of high surface area results. One of the oldest of these so-called skeletal metal catalysts is Raney nickel10,11. Nickel boride is a more recently developed hydrogenation catalyst prepared by the reduction of nickel salts with sodium borohydride12-14. Bimetallic catalysts are often used to achieve selective saturation of a double bond in bifunctional unsaturated systems, e.g. in dienes. Amorphous metal alloys, a newly developed class of metal catalysts15,16, have also been applied in the hydrogenation of alkenes and dienes. 

A more detailed study of the pyrolysis of H3SiMn(CO)5 in a sealed tube for various periods of time at 450°C showed that the volatile products were H2, CO, SiH. , and CH4 a metallic-looking brown film covered the walls of the tube, and an apparently amorphous grey powder was also present (33). Figure 5 shows that hydrogen and methane are produced in increasing amounts as the reaction proceeds, while CO reaches a steady concentration after about 10 min. Silane reaches a maximum concentration after about 5 min, then decreases to zero after 60 min. silane is known to decompose to silicon and hydrogen above about 425°C (368), and its presence is readily accounted for by the disproportionation reaction (109). 

Metals and amorphous boron powder are mixed and then heated and reacted under vacuum or inert gas,... 

However, this reaction is strongly affected by the metal cation of the alkox-ide thus Nb(OBu)5 decomposes in toluene at 573 K yielding amorphous Nb205 powders, whereas Ti(0- Pr)4 is not decomposed under the same reaction... 

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