Elsevier

Acta Metallurgica

Volume 32, Issue 8, August 1984, Pages 1217-1227
Acta Metallurgica

Phase separation and coarsening in FeCrCo alloys

https://doi.org/10.1016/0001-6160(84)90128-7Get rights and content

Abstract

The kinetics of phase separation and coarsening occurring within the miscibility gap in the iron-chromium-cobalt system have been characterized using atom probe field-ion microscopy. The morphology and time evolution of the composition fluctuations indicate that the alloys decompose by continuous phase separation or spinodal decomposition at high supersaturations. The morphology of the two-phase microstructurc was found to be highly interconnected in three-dimensions and characteristic of an isotropic spinodal reaction. The coarsening of the network structures could be fitted to a power law with a time exponent that is significantly less than the classical Lifshitz-Slyozov-Wagner value of one-third.

Résumé

Nous avons caractérisé par la sonde atomique la cinétique de séparation de phases et de grossissement dans la lacune de miscibilité du système fer-chrome-cobalt. La morphologie et l'évolution des fluctuations de composition en fonction du temps montrent que l'alliage se décompose par une séparation continue des phases ou décomposition spinodale, pour les fortes sursaturations. La morphologie de la microstructure diphasée est très imbriquée à trois dimensions, ce qui est caractéristique d'une réaction spinodale isotrope. Nours avons pu faire correspondre le grossissement des structures en réseaux avec une loi de puissance dont l'exposant du temps est nettement inférieur à la valeur classique 13 de Lifshitz, Slyozov et Wagner.

Zusammenfassung

Die Kinetik der Phasenseparation und der Vergröberung, die innerhalb der Mischungslücke in dem System Eisen-Chrom-Kobalt ablaufen, wurden mit der Atomsonde untersucht. Morphologie und zeitliche Entwicklung der Fluktuationen in der Zusammensetzung weisen darauf hin, daß die Legierung sich durch kontinuierliche Phasentrennung oder spinodale Entmischung bei den höchsten Ūbersāttigungen ändern. Die Morphologie der zweiphasigen Mikrostruktur war in drei Dimensionen vernetzt und typisch für eine isotrope spinodale Reaktion. Die Vergröberung der Netzwerkstruktur konnte mit einem Potenzgesetz beschrieben werden, bei dem der Zeitexponent bedeutend kleiner war als der klassische Wert ein Drittel von Lifshitz-Slyozov-Wagner.

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    Present address: University of Pittsburgh, Pittsburgh, PA 15261, U.S.A.

    Present address: Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A.

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