Investigation on the homogenization treatment and element segregation on the microstructure of a γ/γ'-cobalt-based superalloy

Saeed Aliakbari Sani; Hossein Arabi; Shahram Kheirandish; Golamreza Ebrahimi

doi:10.1007/s12613-019-1727-7

Volume 26 Issue 2

Feb. 2019

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Article Navigation > International Journal of Minerals, Metallurgy and Materials > 2019 > 26(2): 222-233

Saeed Aliakbari Sani, Hossein Arabi, Shahram Kheirandish, and Golamreza Ebrahimi, Investigation on the homogenization treatment and element segregation on the microstructure of a γ/γ'-cobalt-based superalloy, Int. J. Miner. Metall. Mater., 26(2019), No. 2, pp. 222-233. https://doi.org/10.1007/s12613-019-1727-7

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Saeed Aliakbari Sani, Hossein Arabi, Shahram Kheirandish, and Golamreza Ebrahimi, Investigation on the homogenization treatment and element segregation on the microstructure of a γ/γ'-cobalt-based superalloy, Int. J. Miner. Metall. Mater., 26(2019), No. 2, pp. 222-233. https://doi.org/10.1007/s12613-019-1727-7

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Research Article

Investigation on the homogenization treatment and element segregation on the microstructure of a γ/γ'-cobalt-based superalloy

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Corresponding author:
Hossein Arabi E-mail: arabi@iust.ac.ir
Received: 24 April 2018; Revised: 5 July 2018; Accepted: 13 July 2018

Abstract

Abstract

The aim of the present study was to investigate the effect of element segregation on the microstructure and γ' phase in a γ/γ' cobalt-based superalloy. Several samples were prepared from a cast alloy and homogenized at 1300℃ for different times, with a maximum of 24 h. A microstructural study of the cast alloy using wavelength-dispersive spectroscopic analysis revealed that elements such as Al, Ti, and Ni segregated mostly within interdendritic regions, whereas W atoms were segregated within dendrite cores. With an increase in homogenization time, segregation decreased and the initial dendritic structure was eliminated. Field-emission scanning electron microscopy micrographs showed that the γ' phases in the cores and interdendritic regions of the as-cast alloy were 392 and 124 nm, respectively. The size difference of γ' was found to be due to the different segregation behaviors of constituent elements during solidification. After homogenization, particularly after 16 h, segregation decreased; thus, the size, chemical composition, and hardness of the precipitated γ' phase was mostly uniform throughout the samples.
- superalloy;
- segregation;
- homogenization;
- microstructure;
- γ' phase

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