Production of Non-Equilibrium Transition Metal Fine Particles by Mechanical and Chemical Fragmentation

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In this project, we tried to produce nonequilibrium metal and compound fine powders using the combined process of mechanical milling and chemical reaction, and observed their structures and magnetic properties. The following is the summary of our experimental results.1) Combined Process of Mechanical Milling and LeachingNonequilibrium precursory particles of Ni-Al, Mn-Al, Ru-Al, Ni-Fe-Al and Cu-Fe-Al were produced using mechanical milling. The main portion of Al was leached out of these milled powders in basic solution. The X-ray diffraction measurements indicate that the nonequilibrium structures, bcc Ni, alpha-Mn, bcc Ru, bcc Ni-Fe and bcc Cu-Fe, retain even after leaching, where Cu-Fe powders are highly oxidized. The DSC traces of these powderes show a exothermic peak owing to nonequilibrium-to equilibrium-phase transformation. Magnetic measurements indicate that bcc Ni and bcc Ru are paramagnetic, while alpha-Mn and bcc Ni-Fe(25at%Fe) are ferromagnetic. These results clearly demons … More trate formation of nonequilibrium phases.2) Enhanced Decomposion of Chemical Solution by Ultrasonic IrradiationPentacarbonyl, Fe(CO)_5 solutions in decane were irradiated using a high-intensity ultrasonic probe and sooty powders were obtained by filtereing and rinsing with dry pentane. The X-ray diffraction experiment show a halo pattern, indicating these powderes are amorphous-like. Magnetization of these powders is one order smaller than that of bulk Fe. This indicates insufficient decomposion of carbonyl solutions, being consistent with presence of C and O detected by the chemical analyzes.3) Homogeneous Complex Formation in Mixed Hydrogel by Mechanical MillingProcesses of complex formation between alumina and titania hydrogels was verified by X-ray diffraction, DSC, NMR and EXAFS.The Knight shift and symmetric to asymmetric change in the of ^<27>Al as well as modification of Ti-K edge EXAFS sepctra clearly demonstratethe chemical bonding, Al-O-Ti is formed during the millig process. Less