Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Effect of Atomization Conditions on Microstructure of Ni-base Superalloy Powder
Tetsuo KATOKatsushi KUSAKAAkira HORATAJiro ICHIKAWA
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JOURNAL FREE ACCESS

1985 Volume 71 Issue 6 Pages 719-726

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Abstract

Many kinds of superalloys are widely being employed as materials for aircrafts, but the segregation is generally apt to occur in cast alloys because of bearing many alloying elements. Accordingly, the powder metallurgy technique has lately been available for the practical production of turbine disc etc. In order to sufficiently apply the improved properties of material, it is necessary to make microstructure of powder as fine as possible.
The authors developed liquefied helium cooling centrifugal atomization technique and made a trial on a fine crystallization of particles by rapid solidification of melt in the process of the atomization. An investigation was made about the various atomization factors which widely control the secondary dendrite arm spacing, SII, as a measure of microstructure.
The following results were obtained.
(1) The most frequent diameter of powder, d(μm), is given as the following equation;
d=4.0×105×R-0.84
where R represents the revolution speed of the disc (rpm).
(2) The following means are effective to make the microstructure finer.
a) The particle size is smaller.
b) The thermal conductivity of the cooling medium gas is higher.
c) The gas pressure of the cooling medium is higher.
d) The gas temperature of the cooling medium is lower.
e) The introducing rate of the cooling medium is higher.
f) The diameter of the atomizing disc is greater and its revolution speed is higher.

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© The Iron and Steel Institute of Japan
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