XY dipolar macrospins on curved surfaces forming ferromagnetic liquid droplets

AEM analysis of solidification catalysts in atomized Fe-Ni

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144395 ◽

1986 ◽

Vol 44 ◽

pp. 584-585

Author(s):

Matthew R. Libera

Keyword(s):

Powder Particle ◽

Alloy Composition ◽

Particle Diameter ◽

Metastable Phases ◽

Liquid Droplets ◽

Nucleation Kinetics ◽

Ni Alloys ◽

Nonequilibrium Solidification

The liquid droplets produced by atomization processes are believed to undergo substantial supercooling during solidification, because the catalytic heterogeneities, for statistical reasons, tend to be isolated in the larger droplets. This supercooling can lead to the nucleation of metastable phases. As part of a study on the effect of liquid supercooling on nonequilibrium solidification, three binary Fe-Ni alloys have been produced by conventional argon atomization (Fe-20Ni, Fe-30Ni, and Fe-40Ni). The primary variables in these experiments are: i) the alloy composition; and ii) the powder particle diameter (inversely proportional to supercooling). Of particular interest in this system is the competitive nucleation kinetics between the stable fee and metastable bec phases. Bcc is expected to nucleate preferentially with decreasing %Ni and decreasing particle diameter.

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HREM observation of NiO growth on submicron spheres of pure nickel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154718 ◽

1989 ◽

Vol 47 ◽

pp. 548-549

Author(s):

C.M. Teng ◽

T.F. Kelly ◽

J.P. Zhang ◽

H.M. Lin ◽

Y.W. Kim

Keyword(s):

Nickel Oxide ◽

Grain Boundaries ◽

Pure Nickel ◽

Submicron Particles ◽

Crystal Formation ◽

Nickel Wire ◽

Liquid Droplets ◽

Oxide Interface ◽

Nickel Chromium ◽

Chromium Alloys

Spherical submicron particles of materials produced by electrohydrodynamic (EHD) atomization have been used to study a variety of materials processes including nucleation of alternative crystallization phases in iron-nickel and nickel-chromium alloys, amorphous solidification in submicron droplets of pure metals, and quasi-crystal formation in nickel-chromium alloys. Some experiments on pure nickel, nickel oxide single crystals, the nickel/nickel(II) oxide interface, and grain boundaries in nickel monoxide have been performed by STEM. For these latter studies, HREM is the most direct approach to obtain particle crystal structures at the atomic level. Grain boundaries in nickel oxide have also been investigated by HREM. In this paper, we present preliminary results of HREM observations of NiO growth on submicron spheres of pure nickel.Small particles of pure nickel were prepared by EHD atomization. For the study of pure nickel, 0.5 mm diameter pure nickel wire (99.9975%) is sprayed directly in the EHD process. The liquid droplets solidify in free-flight through a vacuum chamber operated at about 10-7 torr.

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