Einfluß von Silicium und Titan auf das Oxidationsverhalten von MCrAlY-Legierungen
Einfluß von Silicium und Titan auf das Oxidationsverhalten von MCrAlY-Legierungen
The influence of Si and Ti additions on the oxidation behaviour of Ni-20Cr-IOAl-Y protective cladding aUoys has been investigated. The Si and Ti contents in the model alloys were varied systematicall and the influence on the early oxidation stages as well as on the long-term oxidation was determined...
Saved in:
Personal Name(s): | Clemens, D. (Corresponding author) |
---|---|
Quadakkers, Willem J. / Schubert, F. / Nickel, Hubertus | |
Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
1997
|
Physical Description: |
161 p. |
Document Type: |
Report Book |
Research Program: |
Addenda |
Series Title: |
Berichte des Forschungszentrums Jülich
3444 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
The influence of Si and Ti additions on the oxidation behaviour of Ni-20Cr-IOAl-Y protective cladding aUoys has been investigated. The Si and Ti contents in the model alloys were varied systematicall and the influence on the early oxidation stages as well as on the long-term oxidation was determined in the temperature range 950°C - 1100°C in Ar-20%O2. For the evaluation of the results, a variety of analysis techniques, such as optical metallography, SEM/EDX, SNMS and TEM were applied, in combination with conventional gravimetric analysis. Si and especially Ti were found to have a strong effect on the distribution and composition of phases present in Ni-20Cr-10AI-Y alloys. Especially in the early stages of oxidation there was a significant influence of the phase distribution present on the oxide scale morphology: on the $\beta$-phase mainly the metastable $\theta$-Al$_{2}$O$_{3}$ modification was formed, whereas on the $\gamma$-phase $\alpha$-Al$_{2}$O$_{3}$ was found. After longer oxidation times usuaUy an $\alpha$-Al$_{2}$O$_{3}$-scale was formed on the whole alloy surface. Both elements, but especially Ti, enhanced the selective oxidation of Al by reducing the oxygen potential at the scale/metal interface and promoted the formation of new alumina scales after spalling. It was found that the effects of Si and Ti were closeIy correlated with the amount of Y present in the alloy. High Y contents led to the formation of phases rich in Ni and Y at the alloy grain boundaries which caused severe internaIoxidation. Low Y contents of a below 0.1 %, together with low Si and Ti contents, significantly reduced the tendency forinternal oxidation to occur and thereby improved the long-term oxidation behaviour of Ni-20Cr-10Al-Y alloys. |