Abstract
The sensitivity of thermo-electric power (TEP) measurement to detect the undesired α–α′ phase separation occurring in Cr-rich oxide dispersion strengthened steels was investigated. TEP values were found to increase with time of exposure to 475 °C—the maximum temperature of the miscibility gap in Fe–Cr alloys. Exposure to 650 °C did not induce any changes in the TEP value. By examining the bend contours in dark-field TEM images, α′ precipitates were evidenced in aged PM2000. Using the Fe–XCr–YAl model alloys and X-ray photoelectron spectroscopy, the changes in TEP were traced back to the depletion of Cr from the matrix, caused by the formation of the Cr-rich α′ phase. By quantifying the effect of Cr content on the TEP value of model alloys, it was estimated that following 1000 h of aging, the Cr concentration in the α matrix of PM2000 alloy was reduced from 20 to ~13.5 at.%.
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Acknowledgements
The authors would like to thank Dr. Y. Gelbstein for performing the TEP measurements and Mr. O. Omassi for casting the model alloys. This study was supported by a dedicated collaboration agreement between the Israel Atomic Energy Commission and the Joint Research Centre of the European Commission.
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Pinkas, M., Foxman, Z., Froumin, N. et al. Sensitivity of thermo-electric power measurements to α–α′ phase separation in Cr-rich oxide dispersion strengthened steels. J Mater Sci 50, 4629–4635 (2015). https://doi.org/10.1007/s10853-015-9014-0
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DOI: https://doi.org/10.1007/s10853-015-9014-0