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MATCHING LOCAL COMPOSITION AND MECHANICAL PROPERTY ANISOTROPY OF PREOXIZED (Ni, Pt)Al BOND COATS AFTER THERMAL CYCLING TESTS

García-Herrera, J.E. and Mora-García, A.M. and Alvarado-Orozco, J.M. and Cácerez-Díaz, L.A. and Konitzer, D.G. and Mondragón Rodríguez, G.C. and Schulz, Uwe and Trápaga-Martínerz, G. and Muñoz-Saldaña, J. (2013) MATCHING LOCAL COMPOSITION AND MECHANICAL PROPERTY ANISOTROPY OF PREOXIZED (Ni, Pt)Al BOND COATS AFTER THERMAL CYCLING TESTS. XXII International Materials Research Congress, 11.-15. Aug. 2013, Cancún Mexiko.

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Abstract

Pt-modified nickel aluminide, B2 (Ni,Pt)Al, coatings are used to protect the surface of turbine airfoils against oxidation [1]. However, the lack of ductility of these systems presents a drawback in their performance. At high temperatures several elements diffuse from the superalloy substrate and become incorporated into the B2 phase, which can modify its mechanical properties. This diffusion process also results in a distribution of elements throughout the coating that can change from grain to grain. Few reports on the local, micromechanical properties of B2 (Ni,Pt)Al coatings measured by nanoindentation, taking into account crystal orientation, have been published. No anisotropy effect of elastic modulus in the B2 (Ni,Pt)Al was observed by Durst et al. [2], but their finding remains to be understood, and the effect of local chemical composition is yet to be thoroughly explored. In this work, coupons of Rene-N5 superalloy coated with a B2 (Ni,Pt)Al bond coat were pre-oxidized at different temperatures and oxygen partial pressures (pO2) in order to generate a protective α-Al2O3 scale. An yttria-stabilized zirconia (7YSZ) top-coat layer was subsequently deposited by EB-PVD to complete the thermal barrier coating (TBCs). Finally, the TBCs were subjected to thermal cycling tests, during which the (Ni,Pt)Al was observed to transform from pure B2 to a combination of L10 (martensitic), L12 (ordered fcc), and B2 (ordered bcc) phases. Electron backscattering diffraction (EBSD) was used to identify the crystal orientation of the different phases. The mechanical properties of grains oriented in the [001], [101], and [111] directions were measured by nanoindentation with two different indenter geometries, Berkovich and cono-spherical. No anisotropy of mechanical properties was found using the Berkovich indenter, whereas slight differences were observed with the cono-spherical indenter. Moreover, strong differences in the elastic limit were observed when measuring with the cono-spherical within the same grain, which is attributed to differences in the local chemical composition. Finally, the mechanical properties of the L10 and L12 phases are presented and discussed. References: [1] J. Esslinger and E.E. Affeldt, Transactions of the ASME, Journal of Engineering for Gas Turbines and Power, 121 (1998): 687-690. [2] K. Durst, O. Franke and M. Göken, Proceedings Superalloys (2004): 467-476.

Item URL in elib:https://elib.dlr.de/84684/
Document Type:Conference or Workshop Item (Speech)
Title:MATCHING LOCAL COMPOSITION AND MECHANICAL PROPERTY ANISOTROPY OF PREOXIZED (Ni, Pt)Al BOND COATS AFTER THERMAL CYCLING TESTS
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
García-Herrera, J.E.Cinvestav, Unidad Querétaro MéxicoUNSPECIFIED
Mora-García, A.M.Cinvestav, Unidad Querétaro MéxicoUNSPECIFIED
Alvarado-Orozco, J.M.University of PittsburghUNSPECIFIED
Cácerez-Díaz, L.A.Cinvestav, Unidad Querétaro MéxicoUNSPECIFIED
Konitzer, D.G.General Electric CincinnatiUNSPECIFIED
Mondragón Rodríguez, G.C.guillermo.mondragon-rodriguez (at) dlr.deUNSPECIFIED
Schulz, UweUwe.Schulz (at) dlr.dehttps://orcid.org/0000-0003-0362-8103
Trápaga-Martínerz, G.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Muñoz-Saldaña, J.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Date:13 August 2013
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Thermal barrier coatings, mechanical properties, nanoindentation, phase transformations
Event Title:XXII International Materials Research Congress
Event Location:Cancún Mexiko
Event Type:international Conference
Event Dates:11.-15. Aug. 2013
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems (old)
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > High Temperature and Functional Coatings
Deposited By: Mondragon Rodriguez, Guillermo Cesar
Deposited On:16 Oct 2013 09:52
Last Modified:01 Dec 2018 19:49

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