Berlin 2005 – scientific programme

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M: Metallphysik

M 19: Nanoskalige Materialien II

M 19.5: Talk

Saturday, March 5, 2005, 12:00–12:15, TU H111

Nanoparticles of intermetallic phases extracted from Ni-base alloys — •Giancarlo Pigozzi, Debashis Mukherji, and Gernot Kostorz — ETH Zürich, Institute of Applied Physics, CH-8093 Zürich, Switzerland

Single crystalline nanoparticles of Ni alumides and silicides have been produced by an electrochemical process based on selective dissolution of the matrix phase of a two-phase alloy containing an intermetallic precipitate phase. The precipitates were grown to less than 50 nm mean size by an isothermal aging treatment. Electrochemical potentiometric experiments were performed to determine the appropriate process parameters for the extraction of the nanoparticles. The collection of nanoparticles after the extraction poses a serious challenge. Ultrasonic vibration and centrifuge are employed for separating the nanoparticles from the sample surface and from the liquid bath. Results are presented on characterisation of the microstructure of the alloy and the extracted particles by SEM, TEM, and XRD. The composition control and the control of homogeneity of multicomponent nanoparticles is relatively easy, in this technique. The process is demonstrated presently only at the laboratory scale and even at this scale, only a tiny amount of material (in mg) is obtained when the particles are less than 50 nm in size. Work is in progress to increase the yield.