ISSN:
1573-4889
Keywords:
iridium-aluminum-silicon alloys
;
intermetallic
;
oxidation resistance
;
alumina
;
silica
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The oxidation behavior of iridium-based intermetallics in the ternary iridium-aluminum-silicon system has been investigated. Additions of up to 20 at. % silicon to iridium-aluminum binary alloys reduce the aluminum concentration necessary for the formation of a protective alumina scale from greater than 55 at.% in the absence of silicon to as low as 20 at.% when 20 at.% silicon is present. Ternary iridium-aluminum-silicon alloys with 30–50 at.% aluminum and 8–10 at.% silicon exhibit parabolic oxidation behavior, and the rate constants are in good agreement with those previously determined for binary iridium-aluminum alloys. The oxidation rate of ternary iridium-aluminum-silicon alloys with 10 at.% silicon and 30–40 at.% aluminum deviates from the parabolic-oxidation behavior for alumina scale growth in the later oxidation stage, presumably due to the formation of a silica inner layer. Thermal cycling of the Ir-50 Al-8Si and Ir-60-Al samples does not result in scale spallation due to the coefficient of thermal expansion match between the alumina scale and intermetallic substrate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01196642
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