Sensitivity of thermo-electric power measurements to alpha- alpha' phase separation in Cr-rich oxide dispersion strengthened steels

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.%.

PINKAS Malki;  FOXMAN Zvi;  FROUMIN Nataly;  HAEHNER Peter;  MESHI Louisa; 

2015-07-09

SPRINGER

JRC96214

0022-2461,   

http://link.springer.com/article/10.1007%2Fs10853-015-9014-0,    https://publications.jrc.ec.europa.eu/repository/handle/JRC96214,   

10.1007/s10853-015-9014-0,