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Advances in Materials Science and Engineering
Volume 2015 (2015), Article ID 485626, 7 pages
http://dx.doi.org/10.1155/2015/485626
Research Article

Ostwald Ripening Process of Coherent β′ Precipitates during Aging in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 Alloys

Instituto Politécnico Nacional (ESIQIE-CNMN), Apartado Postal 118-556, 07051 Mexico, DF, Mexico

Received 26 September 2014; Revised 16 December 2014; Accepted 6 January 2015

Academic Editor: Jörg M. K. Wiezorek

Copyright © 2015 N. Cayetano-Castro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The Ostwald ripening process was studied in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 alloys after aging at 750, 850, and 950°C for different times. The microstructural evolution shows a rounded cube morphology (Fe, Ni)Al β′ precipitates aligned in the ferrite matrix, which changes to elongated plates after prolonged aging. The variation of the equivalent radii of precipitates with time follows the modified Lifshitz-Slyozov-Wagner theory for diffusion-controlled coarsening. Thermo-Calc analysis shows that the chromium content is richer in the matrix than in the precipitates which causes higher hardness and coarsening resistance in the aged Fe0.74Ni0.10Al0.15Cr0.01 alloy.