Kinetic process of the phase separation in the alloy Ni3Al 0.52V0.48

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Abstract

In the Ni3Al0.52V0.48 alloy, D0 22 precipitation in the supersaturated L12 matrix has been found to stagnate due to the occurrence of the L12 → L1 2 + D022 → L12 structural change in an isothermal process. In this paper, we experimentally show the variation of the L12 and D022 chemical compositions during the structural change. Our results reveal that the transient D022 formation accompanies a large concentration fluctuation, while the final L12 composition reverts back to the initial L12 one. It is also found that the average V content of the D022 regions decreases together with the change in the L12/D022 habit planes from the {100} to {110} ones. These experimental results are indicative of the suppression of atomic diffusion and subsequent redistribution of Al and V in the L12 matrix, resulting in D022 annihilation. It is proposed that jump site selectivity and cooperative atomic migration in the L12 structure are important factors in the suppression of atomic diffusion. Because the appearance of these factors correlates well with the vacancy concentration of the L12 matrix, it is concluded that the stagnation of D022 precipitation represents one kinetic process under the present thermodynamic path.

Original languageEnglish
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number9
DOIs
Publication statusPublished - 2004 Sep

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ASJC Scopus subject areas

  • Condensed Matter Physics

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