| Budget Amount *help |
¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1993: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
The aim of this study is to investigate a crystak growth mechanism of ultrafine iron-nickel alloy particles prepared by a gas-evaporation technique, that is, a method preparing ultrafine particles by evaporation ot material in an atomosphere of inert gas at a low pressure. It is known that there coexist two phases of alpha (bcc structure) and gamma (fcc structure) in the wide composition range at a high temperature. Three kinds of starting materials were evaporeted from a tungsten boat, in order to study the difference of growth mechanizm due to the preparation conditions. For the particles grown from mixed powder material, the particle surfaces were oxidized, because of the oxygen molecules contained in the powder. The particles grown from wound wires of iron and nickel consisted of a single phase of either alpha or gamma, inspite of the composition of starting material wires. Most of the particles grown from Fe-36 at% Ni foil consisted of a single phase of either alpha or gamma, and they formed alternating long chains. This may originate partly because of the spatiotemporal fluctuation. of iron and nickel vapor densities at the nucleation stages of the alpha and gamma particles. The other possibility is the quenching effect. In the present case, the single gamma phase at elevated temperature is quenched through the cooling process. In fact, on rare occasions, particles consisting of two phases were observed among the single-phase ones. For the two-phase particles, the alpha phase precipitated from the gamma phase.
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