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Microstructural evolution and thermal stability Associated with a Gas-Atomized Cu-Nb Alloy

Microstructural evolution and thermal stability Associated with a Gas-Atomized Cu-Nb Alloy High-pressure inert gas atomization (HPGA) has been used to produce rapidly solidified Cu-21Nb-2Mo (weight percent) powders with a range of particle sizes and microstructures. The associated microstructures depend on particle size. Specifically, fine-scale particles (\s15 μm@#@) are characterized by a predominance of multiphase spheroids and a small population of Nb-based dendrites in an almost pure matrix of Cu. In contrast, large particles (45 to 75 μm@#@) contain only Nb-based dendrites in a Cu matrix. The volume fraction of the dispersed constituent is much higher in the former instance than in the latter. The change in microstructure with particle size is analyzed in terms of both the amount of undercooling and cooling rate of the liquid droplets prior to and during solidification. In particular, the large undercoolings in the fine particles are believed to induce a nonequilibrium liquid phase separation which results in a high volume fraction of spheroidal, multiphase Nb-Cu particles within a Cu-rich matrix containing Nb-rich dendrites. High-temperature (900 °C) isothermal annealing treatments have also been performed on consolidated material to determine the inherent thermal stability of these microstructures. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Metallurgical and Materials Transactions A Springer Journals

Microstructural evolution and thermal stability Associated with a Gas-Atomized Cu-Nb Alloy

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References (17)

Publisher
Springer Journals
Copyright
Copyright © The Minerals, Metals and Materials Society, and ASM International 1992
ISSN
1073-5623
eISSN
1543-1940
DOI
10.1007/bf02646009
Publisher site
See Article on Publisher Site

Abstract

High-pressure inert gas atomization (HPGA) has been used to produce rapidly solidified Cu-21Nb-2Mo (weight percent) powders with a range of particle sizes and microstructures. The associated microstructures depend on particle size. Specifically, fine-scale particles (\s15 μm@#@) are characterized by a predominance of multiphase spheroids and a small population of Nb-based dendrites in an almost pure matrix of Cu. In contrast, large particles (45 to 75 μm@#@) contain only Nb-based dendrites in a Cu matrix. The volume fraction of the dispersed constituent is much higher in the former instance than in the latter. The change in microstructure with particle size is analyzed in terms of both the amount of undercooling and cooling rate of the liquid droplets prior to and during solidification. In particular, the large undercoolings in the fine particles are believed to induce a nonequilibrium liquid phase separation which results in a high volume fraction of spheroidal, multiphase Nb-Cu particles within a Cu-rich matrix containing Nb-rich dendrites. High-temperature (900 °C) isothermal annealing treatments have also been performed on consolidated material to determine the inherent thermal stability of these microstructures.

Journal

Metallurgical and Materials Transactions ASpringer Journals

Published: Aug 1, 1992

Keywords: Metallurgical Transaction; Powder Particle; Powder Size; Liquid Phase Separation; Large Powder

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