2134/15323
David M. Gorman
David M.
Gorman
Rebecca Higginson
Rebecca
Higginson
H. Du
H.
Du
G. McColvin
G.
McColvin
A.T. Fry
A.T.
Fry
Rachel Thomson
Rachel
Thomson
Microstructural analysis of IN617 and IN625 oxidised in the presence of steam for use in ultra-supercritical power plant
Loughborough University
2014
IN617
IN625
Steam oxidation
Voids
Internal oxidation
Materials Engineering not elsewhere classified
Condensed Matter Physics
2014-07-24 13:59:18
Journal contribution
https://repository.lboro.ac.uk/articles/journal_contribution/Microstructural_analysis_of_IN617_and_IN625_oxidised_in_the_presence_of_steam_for_use_in_ultra-supercritical_power_plant/9235061
The nickel based alloys IN617 and IN625 that have been selected for their candidacy in the construction of the hottest regions of the supercritical steam cycle have been oxidised under isothermal conditions at 750 °C and atmospheric pressure in atmospheres of 100 % steam, 50/50 % steam/argon and air for up to 4,200 h. Both alloys developed a thin protective oxide under each condition. Scale thickness measurements using SEM micrographs were performed and showed that exposures in steam exhibited a higher rate of scale formation than exposures in air in both alloys. IN617 developed an extensive internal network of alumina which resulted in the formation of alloy protrusions into the scale altering scale growth kinetics, IN625 also formed alumina to a lesser extent. Voids formed in the matrix below the scale in both alloys in each environment. The extent of alumina formation alters the void morphology which eventually impacts the scale growth rate as inward scale growth occurred into the voids in IN625 but not in IN617.