Sensitivity of thermo-electric power measurements to α–α′ 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.%.

[1]  Philippe Dubuisson,et al.  ODS Ferritic/martensitic alloys for Sodium Fast Reactor fuel pin cladding , 2012 .

[2]  Philippe Dubuisson,et al.  CEA developments of new ferritic ODS alloys for nuclear applications , 2009 .

[3]  D. Mari,et al.  Tempering effects on a martensitic high carbon steel , 2004 .

[4]  Shigeharu Ukai,et al.  Perspective of ODS alloys application in nuclear environments , 2002 .

[5]  P. Guyot,et al.  Coherent precipitation effect on thermo-power of AlCu alloys , 1988 .

[6]  Yasuhiro Kawaguchi,et al.  Mechanism of the change in thermoelectric power of cast duplex stainless steel due to thermal aging , 2002 .

[7]  Michael K Miller,et al.  Phase separation kinetics in a Fe–Cr–Al alloy , 2012 .

[8]  Markus Niffenegger,et al.  Application of the Seebeck effect for monitoring of neutron embrittlement and low-cycle fatigue in nuclear reactor steel , 2005 .

[9]  A. D. Bremaecker.  Past research and fabrication conducted at SCK•CEN on ferritic ODS alloys used as cladding for FBR’s fuel pins , 2012 .

[10]  B Acosta,et al.  Evaluation of irradiation damage effect by applying electric properties based techniques , 2004 .

[11]  B. Fultz,et al.  Transmission electron microscopy and diffractometry of materials , 2001 .

[12]  K. F. Russell,et al.  Phase separation in PM 2000™ Fe-base ODS alloy : Experimental study at the atomic level , 2008 .

[13]  R. Barnard,et al.  Thermoelectricity in Metals and Alloys , 1974 .

[14]  J. W. Gahn.  Hardening by spinodal decomposition , 1963 .

[15]  C. Kittel.  Introduction to solid state physics , 1954 .

[16]  P. M. Giles,et al.  High‐Pressure α⇄ε Martensitic Transformation in Iron , 1971 .

[17]  E. Diegele,et al.  Present development status of EUROFER and ODS-EUROFER for application in blanket concepts , 2005 .

[18]  N. Mott,et al.  The Theory of the Properties of Metals and Alloys , 1933 .

[19]  A. Almazouzi,et al.  Development of oxides dispersion strengthened steels for high temperature nuclear reactor applications , 2009 .

[20]  Yasuhiro Kawaguchi,et al.  Applications of Thermoelectric Power Measurement to Deterioration Diagnosis of Nuclear Material and Its Principle , 2004 .

[21]  Daniel D. Pollock,et al.  Thermoelectricity : theory, thermometry, tool , 1985 .

[22]  C. Gorter,et al.  Bemerkungen über thermokraft und widerstand , 1935 .

[23]  C. Capdevila,et al.  Influence of the α-α' phase separation on the tensile properties of Fe-base ODS PM 2000 alloy , 2010 .

[24]  Satoru Kobayashi,et al.  Mapping of 475 °C embrittlement in ferritic Fe–Cr–Al alloys , 2010 .

[25]  M. Niffenegger,et al.  Monitoring the embrittlement of reactor pressure vessel steels by using the Seebeck coefficient , 2009 .

[26]  C. Barbosa,et al.  Thermoelectrical power analysis of precipitation in 6013 aluminum alloy , 2008 .